.\" Copyright (c) 1983 Eric P. Allman
.\" Copyright (c) 1983, 1993
.\" The Regents of the University of California. All rights reserved.
.\" %sccs.include.redist.roff%
.\" @(#)op.me 8.17 (Berkeley) %G%
.\" eqn op.me | pic | troff -me
.eh 'SMM:08-%''Sendmail Installation and Operation Guide'
.oh 'Sendmail Installation and Operation Guide''SMM:08-%'
.\" SD is lib if sendmail is installed in /usr/lib, sbin if in /usr/sbin
.\" SB is bin if newaliases/mailq are installed in /usr/bin, ucb if in /usr/ucb
.b "INSTALLATION AND OPERATION GUIDE"
University of California, Berkeley
implements a general purpose internetwork mail routing facility
*UNIX is a trademark of Bell Laboratories.
It is not tied to any one transport protocol \*-
its function may be likened to a crossbar switch,
relaying messages from one domain into another.
it can do a limited amount of message header editing
to put the message into a format that is appropriate
for the receiving domain.
All of this is done under the control of a configuration file.
Due to the requirements of flexibility
the configuration file can seem somewhat unapproachable.
However, there are only a few basic configurations
for which standard configuration files have been supplied.
Most other configurations
can be built by adjusting an existing configuration files
RFC822 (Internet Mail Format Protocol),
RFC821 (Simple Mail Transport Protocol),
RFC1123 (Internet Host Requirements),
RFC1425 (SMTP Service Extensions).
is designed to work in a wider world,
in many cases it can be configured to exceed these protocols.
These cases are described herein.
without the need for monitoring,
it has a number of features
that may be used to monitor or adjust the operation
under unusual circumstances.
These features are described.
Section one describes how to do a basic
explains the day-to-day information you should know
to maintain your mail system.
If you have a relatively normal site,
these two sections should contain sufficient information
describes some parameters that may be safely tweaked.
has information regarding the command line arguments.
contains the nitty-gritty information about the configuration
This section is for masochists
and people who must write their own configuration file.
gives a brief description of differences
The appendixes give a brief
but detailed explanation of a number of features
not described in the rest of the paper.
.sh 1 "BASIC INSTALLATION"
There are two basic steps to installing
The hard part is to build the configuration table.
that describes the mailers it knows about,
how to rewrite the message header,
and the settings of various options.
Although the configuration table is quite complex,
a configuration can usually be built
by adjusting an existing off-the-shelf configuration.
The second part is actually doing the installation,
i.e., creating the necessary files, etc.
The remainder of this section will describe the installation of
assuming you can use one of the existing configurations
and that the standard installation parameters are acceptable.
All pathnames and examples
are given from the root of the
.i /usr/src/usr.\*(SD/sendmail
If you are loading this off the tape,
continue with the next session.
If you have a running binary already on your system,
you should probably skip to section 1.2.
.sh 2 "Compiling Sendmail"
If you are running on a 4.4BSD system,
On other systems, you may have to make some other adjustments.
.sh 3 "Old versions of make"
If you are not running the new version of
you will probably have to use
This file does not assume several new syntaxes,
syntax in macro definition
.sh 3 "Compilation flags"
supports two different formats
available on nearly all systems around today.
This was the preferred format prior to 4.4BSD.
It allows such complex things as multiple databases
and closing a currently open database.
The new database package from Berkeley.
If you have this, use it.
You can define this in conjunction with one of the other two;
but when a new database is created it will be in NEWDB format.
if you have NEWDB, NDBM, and NIS defined,
will create both new and old versions of the alias file
This is required because the Sun NIS/YP system
reads the DBM version of the alias file.
If neither of these are defined,
reads the alias file into memory on every invocation.
This can be slow and should be avoided.
System V based systems can define
to make several small adjustments.
This changes the handling of timezones
and uses the much less efficient
These can be specified separately using the compilation flags
routine in your system library, define the UNSETENV compilation flag.
You may also have to define the compilation variable LA_TYPE
to describe how your load average is computed.
This and other flags are detailed in section 6.1.
.sh 3 "Compilation and installation"
After making the local system configuration described above,
You should be able to compile and install the system.
Compilation can be performed using
\**where you may have to replace
.q "make \-f Makefile.dist"
You may be able to install using
This should install the binary in
On 4.4BSD systems it will also format and install man pages.
.sh 2 "Configuration Files"
cannot operate without a configuration file.
The configuration defines the mail systems understood at this site,
how to forward email to remote mail systems,
and a number of tuning parameters.
This configuration file is detailed
in the later portion of this document.
configuration can be daunting at first.
and the mail configuration reflects that.
The distribution includes an m4-based configuration package
that hides a lot of the complexity.
These configuration files are simpler than old versions
largely because the world has become simpler;
text-based host files are officially eliminated,
hosts behind a registered internet gateway.
These files also assume that most of your neighbors
use domain-based UUCP addressing;
instead of naming hosts as
The configuration files can be customized to work around this,
I haven't tested these yet on an isolated LAN environment
with a single UUCP connection to the outside world.
If you are in such an environment,
sendmail@CS.Berkeley.EDU.
Our configuration files are processed by
to facilitate local customization;
contains the source files.
This directory contains several subdirectories:
Both site-dependent and site-independent descriptions of hosts.
These can be literal host names
when the hosts are gateways
or more general descriptions
as a general description of an SMTP-connected host
as a general description of a UUCP-connected host).
(``Master Configuration'')
are the input descriptions;
the output is in the corresponding
The general structure of these files is described below.
Site-dependent subdomain descriptions.
These are tied to the way your organization wants to do addressing.
is our description for hosts in the CS.Berkeley.EDU subdomain
that want their individual hostname to be externally visible;
is the same except that the hostname is hidden
(everything looks like it comes from CS.Berkeley.EDU).
These are referenced using the
Definitions of specific features that some particular host in your site
These are referenced using the
to read an /etc/sendmail.cw file on startup
to find the set of local names).
Local hacks, referenced using the
The point of having them here is to make it clear that they smell.
include files that have information common to all configuration files.
This can be thought of as a
Defined mailer types in this distribution are
Definitions describing various operating system environments
(such as the location of support files).
These are referenced using the
You shouldn't have to mess with these.
Local site configuration information,
such as UUCP connectivity.
They normally contain lists of site information, for example:
They are referenced using the SITECONFIG macro:
SITECONFIG(site.config.file, name_of_site, X)
is the macro/class name to use.
(indicating locally connected hosts)
for up to three remote UUCP hubs.
If you are in a new domain
you will probably want to create a
This consists primarily of relay definitions:
for example, Berkeley's domain definition
only the UUCP relay is particularly specific
All of these are internet-style domain names.
Please check to make certain they are reasonable for your domain.
Subdomains at Berkeley are also represented in the
is the Computer Science subdomain with the local hostname shown
makes users appear to be from the CS.Berkeley.EDU subdomain
(with no local host information included).
You will probably have to update this directory
to be appropriate for your domain.
You will have to use or create
subdirectory for your hosts.
.sh 2 "Details of Installation Files"
This subsection describes the files that
.sh 3 "/usr/\*(SD/sendmail"
is located in /usr/\*(SD\**.
on 4.4BSD and newer systems;
many systems install it in
I understand it is in /usr/ucblib
It should be setuid root.
should be owned by root, mode 755\**.
\**Some vendors ship them owned by bin;
this creates a security hole that is not actually related to
Other important directories that should have restrictive ownerships
/bin, /usr/bin, /etc, /usr/etc, /lib, and /usr/lib.
This is the configuration file for
This is the only non-library file name compiled into
\**The system libraries can reference other files;
in particular, system library subroutines that
Some older systems install it in
.b /usr/lib/sendmail.cf .
If you want to move this file,
The configuration file is normally created
using the distribution files described above.
If you have a particularly unusual system configuration
you may need to create a special version.
The format of this file is detailed in later sections
.sh 3 "/usr/\*(SB/newaliases"
If you are running delivermail,
This can just be a link to
rm \-f /usr/\*(SB/newaliases
ln /usr/\*(SD/sendmail /usr/\*(SB/newaliases
This can be installed in whatever search path you prefer
.sh 3 "/var/spool/mqueue"
should be created to hold the mail queue.
This directory should be mode 700
The actual path of this directory
The system aliases are held in
which includes some aliases which
cp lib/aliases /etc/aliases
You should extend this file with any aliases that are apropos to your system.
looks at a version of these files maintained by the
These are stored either in
depending on which database package you are using.
These can initially be created as empty files,
but they will have to be initialized promptly.
These should be mode 644:
cp /dev/null /etc/aliases.dir
cp /dev/null /etc/aliases.pag
routines preset the mode reasonably,
so this step can be skipped.
The actual path of this file
It will be necessary to start up the
daemon when your system reboots.
This daemon performs two functions:
it listens on the SMTP socket for connections
(to receive mail from a remote system)
and it processes the queue periodically
to insure that mail gets delivered when hosts come up.
Add the following lines to
in the area where it is starting up the daemons:
if [ \-f /usr/\*(SD/sendmail \-a \-f /etc/sendmail.cf ]; then
(cd /var/spool/mqueue; rm \-f [lnx]f*)
/usr/\*(SD/sendmail \-bd \-q30m &
echo \-n ' sendmail' >/dev/console
commands insure that all lock files have been removed;
extraneous lock files may be left around
if the system goes down in the middle of processing a message.
The line that actually invokes
causes it to listen on the SMTP port,
causes it to run the queue every half hour.
Some people use a more complex startup script,
removing zero length qf files and df files for which there is no qf file.
# remove zero length qf files
echo \-n " <zero: $qffile>" > /dev/console
# rename tf files to be qf if the qf does not exist
qffile=`echo $tffile | sed 's/t/q/'`
if [ \-r $tffile \-a ! \-f $qffile ]
echo \-n " <recovering: $tffile>" > /dev/console
echo \-n " <extra: $tffile>" > /dev/console
# remove df files with no corresponding qf files
qffile=`echo $dffile | sed 's/d/q/'`
if [ \-r $dffile \-a ! \-f $qffile ]
echo \-n " <incomplete: $dffile>" > /dev/console
mv $dffile `echo $dffile | sed 's/d/D/'`
# announce files that have been saved during disaster recovery
echo \-n " <panic: $xffile>" > /dev/console
If you are not running a version of UNIX
that supports Berkeley TCP/IP,
.sh 3 "/usr/lib/sendmail.hf"
This is the help file used by the SMTP
cp lib/sendmail.hf /usr/lib
The actual path of this file
If you wish to collect statistics
you should create the file
cp /dev/null /etc/sendmail.st
chmod 666 /etc/sendmail.st
It is printed with the program
.q mailstats/mailstats.c.
The actual path of this file
.sh 3 "/usr/\*(SB/newaliases"
(i.e., will rebuild the alias database;
This should be a link to /usr/\*(SD/sendmail.
will print the contents of the mail queue;
This should be a link to /usr/\*(SD/sendmail.
.sh 1 "NORMAL OPERATIONS"
The system log is supported by the
Each line in the system log
the name of the machine that generated it
(for logging from several machines
over the local area network),
or an equivalent installed,
you will be able to do logging.
There is a large amount of information that can be logged.
The log is arranged as a succession of levels.
only extremely strange situations are logged.
even the most mundane and uninteresting events
are recorded for posterity.
are reserved for debugging purposes.
Levels from 11\-64 are reserved for verbose information
that some sites might want.
A complete description of the log levels
The mail queue should be processed transparently.
However, you may find that manual intervention is sometimes necessary.
if a major host is down for a period of time
the queue may become clogged.
ought to recover gracefully when the host comes up,
you may find performance unacceptably bad in the meantime.
.sh 3 "Printing the queue"
The contents of the queue can be printed
This will produce a listing of the queue id's,
the date the message entered the queue,
and the sender and recipients.
.sh 3 "Forcing the queue"
should run the queue automatically
The algorithm is to read and sort the queue,
and then to attempt to process all jobs in order.
When it attempts to run the job,
first checks to see if the job is locked.
If so, it ignores the job.
There is no attempt to insure that only one queue processor
since there is no guarantee that a job cannot take forever
does include heuristics to try to abort jobs
that are taking absurd amounts of time;
technically, this violates RFC 821, but is blessed by RFC 1123).
Due to the locking algorithm,
it is impossible for one job to freeze the entire queue.
an uncooperative recipient host
can accumulate many processes in your system.
there is no completely general way to solve this.
you may find that a major host going down
may create a prohibitively large queue.
spending an inordinate amount of time
This situation can be fixed by moving the queue to a temporary place
and creating a new queue.
The old queue can be run later when the offending host returns to service.
it is acceptable to move the entire queue directory:
mv mqueue omqueue; mkdir mqueue; chmod 700 mqueue
You should then kill the existing daemon
(since it will still be processing in the old queue directory)
To run the old mail queue,
run the following command:
/usr/\*(SD/sendmail \-oQ/var/spool/omqueue \-q
flag specifies an alternate queue directory
flag says to just run every job in the queue.
If you have a tendency toward voyeurism,
flag to watch what is going on.
When the queue is finally emptied,
you can remove the directory:
.sh 2 "The Alias Database"
The alias database exists in two forms.
The aliases are of the form
Only local names may be aliased;
eric@prep.ai.MIT.EDU: eric@CS.Berkeley.EDU
will not have the desired effect.
Aliases may be continued by starting any continuation lines
Blank lines and lines beginning with a sharp sign
The second form is processed by the
This form is in the files
actually uses to resolve aliases.
This technique is used to improve performance.
For example, the specification:
OAnis:mail.aliases@my.nis.domain
will first search the /etc/aliases file
Additional flags can be added after the colon
OAnis:-N mail.aliases@my.nis.domain
will search the appropriate NIS map and always include null bytes in the key.
.sh 3 "Rebuilding the alias database"
The DB or DBM version of the database
may be rebuilt explicitly by executing the command
This is equivalent to giving
option is specified in the configuration,
will rebuild the alias database automatically
Auto-rebuild can be dangerous
on heavily loaded machines
if it might take more than five minutes
there is a chance that several processes will start the rebuild process
If you have multiple aliases databases specified,
flag rebuilds all the database types it understands
(for example, it can rebuild dbm databases but not nis databases).
.sh 3 "Potential problems"
There are a number of problems that can occur
process accessing the DBM version
while it is only partially built.
This can happen under two circumstances:
One process accesses the database
while another process is rebuilding it,
or the process rebuilding the database dies
(due to being killed or a system crash)
before completing the rebuild.
Sendmail has two techniques to try to relieve these problems.
First, it ignores interrupts while rebuilding the database;
this avoids the problem of someone aborting the process
leaving a partially rebuilt database.
at the end of the rebuild
it adds an alias of the form
(which is not normally legal).
will access the database,
it checks to insure that this entry exists\**.
option is required in the configuration
for this action to occur.
This should normally be specified
If an error occurs on sending to a certain address,
where the submitter of the list
has no control over the maintenance of the list itself;
in this case the list maintainer would be the owner of the list.
unix-wizards: eric@ucbarpa, wnj@monet, nosuchuser,
owner-unix-wizards: eric@ucbarpa
to get the error that will occur
List owners also cause the envelope sender address to be modified.
The contents of the owner alias are used if they point to a single user,
otherwise the name of the alias itself is used.
For this reason, and to obey Internet conventions,
a typical scheme would be:
list: some, set, of, addresses
list-request: list-admin-1, list-admin-2, ...
.sh 2 "User Information Database"
with the user information database
and you have specified one or more databases using the
the databases will be searched for a
If found, the mail will be sent to the specified address.
If the first token passed to user part of the
the at sign will be stripped off
and this step will be skipped.
.sh 2 "Per-User Forwarding (.forward Files)"
As an alternative to the alias database,
any user may put a file with the name
in his or her home directory.
redirects mail for that user
to the list of addresses listed in the .forward file.
For example, if the home directory for user
has a .forward file with contents:
then any mail arriving for
will be redirected to the specified accounts.
Actually, the configuration file defines a sequence of filenames to check.
By default, this is the user's .forward file,
but can be defined to be more generally using the
you will have to inform your user base of the change;
\&.forward is pretty well incorporated into the collective subconscious.
.sh 2 "Special Header Lines"
Several header lines have special interpretations
defined by the configuration file.
Others have interpretations built into
that cannot be changed without changing the code.
These builtins are described here.
.sh 3 "Return-Receipt-To:"
a message will be sent to any specified addresses
when the final delivery is complete,
when successfully delivered to a mailer with the
flag (local delivery) set in the mailer descriptor.
If errors occur anywhere during processing,
this header will cause error messages to go to
This is intended for mailing lists.
The Errors-To: header was created in the bad old days
when UUCP didn't understand the distinction between an envelope and a header;
this was a hack to provide what should now be passed
as the envelope sender address.
If a message comes in with no recipients listed in the message
(in a To:, Cc:, or Bcc: line)
header line for any recipients it is aware of.
This is not put in as a standard recipient line
to warn any recipients that the list is not complete.
At least one recipient line is required under RFC 822.
.sh 2 "IDENT Protocol Support"
supports the IDENT protocol as defined in RFC 1413.
Although this enhances identification
of the author of an email message
by doing a ``call back'' to the originating system to include
the owner of a particular TCP connection
it is in no sense perfect;
a determined forger can easily spoof the IDENT protocol.
The following description is excerpted from RFC 1413:
6. Security Considerations
The information returned by this protocol is at most as trustworthy
as the host providing it OR the organization operating the host. For
example, a PC in an open lab has few if any controls on it to prevent
a user from having this protocol return any identifier the user
wants. Likewise, if the host has been compromised the information
returned may be completely erroneous and misleading.
The Identification Protocol is not intended as an authorization or
access control protocol. At best, it provides some additional
auditing information with respect to TCP connections. At worst, it
can provide misleading, incorrect, or maliciously incorrect
The use of the information returned by this protocol for other than
auditing is strongly discouraged. Specifically, using Identification
Protocol information to make access control decisions - either as the
primary method (i.e., no other checks) or as an adjunct to other
methods may result in a weakening of normal host security.
An Identification server may reveal information about users,
entities, objects or processes which might normally be considered
private. An Identification server provides service which is a rough
analog of the CallerID services provided by some phone companies and
many of the same privacy considerations and arguments that apply to
the CallerID service apply to Identification. If you wouldn't run a
"finger" server due to privacy considerations you may not want to run
The complete list of arguments to
is described in detail in Appendix A.
Some important arguments are described here.
The amount of time between forking a process
this can be relatively large,
since it will only be relevant
when a host that was down comes back up.
it should be relatively short,
since it defines the maximum amount of time that a message
RFC 1123 section 5.3.1.1 says that this value should be at least 30 minutes
(although that probably doesn't make sense if you use ``queue-only'' mode).
If you allow incoming mail over an IPC connection,
you should have a daemon running.
This should be set by your
flag may be combined in one call:
/usr/\*(SD/sendmail \-bd \-q30m
.sh 2 "Forcing the Queue"
In some cases you may find that the queue has gotten clogged for some reason.
You can force a queue run
It is entertaining to use the
when this is done to watch what happens:
/usr/\*(SD/sendmail \-q \-v
You can also limit the jobs to those with a particular queue identifier,
using one of the queue modifiers.
restricts the queue run to jobs that have the string
somewhere in one of the recipient addresses.
limits the run to particular senders and
limits it to particular identifiers.
There are a fairly large number of debug flags
Each debug flag has a number and a level,
where higher levels means to print out more information.
The convention is that levels greater than nine are
they print out so much information that you wouldn't normally
want to see them except for debugging that particular piece of code.
Debug flags are set using the
debug-flag: \fB\-d\fP debug-list
debug-list: debug-option [ , debug-option ]
debug-option: debug-range [ . debug-level ]
debug-range: integer | integer \- integer
where spaces are for reading ease only.
\-d12 Set flag 12 to level 1
\-d12.3 Set flag 12 to level 3
\-d3-17 Set flags 3 through 17 to level 1
\-d3-17.4 Set flags 3 through 17 to level 4
For a complete list of the available debug flags
you will have to look at the code
(they are too dynamic to keep this documentation up to date).
.sh 2 "Trying a Different Configuration File"
An alternative configuration file
can be specified using the
/usr/\*(SD/sendmail \-Ctest.cf
uses the configuration file
in the current directory.
.sh 2 "Changing the Values of Options"
Options can be overridden using the
/usr/\*(SD/sendmail \-oT2m
(timeout) option to two minutes
Some options have security implications.
Sendmail allows you to set these,
but refuses to run as root thereafter.
Many SMTP implementations do not fully implement the protocol.
For example, some personal computer based SMTPs
do not understand continuation lines in reply codes.
These can be very hard to trace.
If you suspect such a problem, you can set traffic logging using the
/usr/\*(SD/sendmail \-X /tmp/traffic -bd
will log all traffic in the file
This logs a lot of data very quickly and should never be used
during normal operations.
After starting up such a daemon,
force the errant implementation to send a message to your host.
All message traffic in and out of
including the incoming SMTP traffic,
will be logged in this file.
There are a number of configuration parameters
depending on the requirements of your site.
using an option in the configuration file.
Most of these options have appropriate defaults for most sites.
sites having very high mail loads may find they need to tune them
as appropriate for their mail load.
sites experiencing a large number of small messages,
many of which are delivered to many recipients,
may find that they need to adjust the parameters
dealing with queue priorities.
All time intervals are set
represents ten minutes, whereas
represents two and a half hours.
The full set of scales is:
specifies how often a sub-daemon will run the queue.
This is typically set to between fifteen minutes
RFC 1123 section 5.3.1.1 recommends that this be at least 30 minutes.
It is possible to time out when reading the standard input
or when reading from a remote SMTP server.
These timeouts are set using the
option in the configuration file.
The argument is a list of
The recognized keywords, their default values, and the minimum values
allowed by RFC 1123 section 5.3.2 are:
The wait for the initial 220 greeting message
The wait for a reply from a HELO or EHLO command
This may require a host name lookup, so
five minutes is probably a reasonable minimum.
The wait for a reply from a MAIL command
The wait for a reply from a RCPT command
because it could be pointing at a list
that takes a long time to expand.
The wait for a reply from a DATA command
The wait for reading a data block
(that is, the body of the message).
This should be long because it also applies to programs
which have no guarantee of promptness.
The wait for a reply from the dot terminating a message.
If this is shorter than the time actually needed
for the receiver to deliver the message,
duplicates will be generated.
This is discussed in RFC 1047.
The wait for a reply from a RSET command
The wait for a reply from a QUIT command
The wait for a reply from miscellaneous (but short) commands
such as NOOP (no-operation) and VERB (go into verbose mode).
the time to wait for another command.
The timeout waiting for a reply to an IDENT query
For compatibility with old configuration files,
if no ``keyword='' is specified,
all the timeouts marked with \(dg are set to the indicated value.
Many of the RFC 1123 minimum values
was designed to the RFC 822 protocols,
which did not specify read timeouts;
does not guarantee to reply to messages promptly.
command specifying a mailing list
will expand and verify the entire list;
a large list on a slow system
may take more than five minutes\**.
\**This verification includes looking up every address
this involves network delays,
and can in some cases can be considerable.
I recommend a one hour timeout \*-
since this failure is rare,
a long timeout is not onerous
and may ultimately help reduce network load.
Orcommand=25m,datablock=3h
sets the server SMTP command timeout to 25 minutes
and the input data block timeout to three hours.
After sitting in the queue for a few days,
This is to insure that at least the sender is aware
of the inability to send a message.
The timeout is typically set to three days.
This timeout is set using the
option in the configuration file.
The time of submission is set in the queue,
rather than the amount of time left until timeout.
As a result, you can flush messages that have been hanging
with a short message timeout.
/usr/\*(SD/sendmail \-oT1d \-q
and flush anything that is one day old.
Since this option is global,
know how long another host outside your domain will be down,
a five day timeout is recommended.
This allows a recipient to fix the problem even if it occurs
at the beginning of a long weekend.
RFC 1123 section 5.3.1.1 says that this parameter
should be ``at least 4\-5 days''.
option can also take a second timeout indicating a time after which
a warning message should be sent;
the two timeouts are separated by a slash.
causes email to fail after five days,
but a warning message will be sent after four hours.
This should be large enough that the message will have been tried
.sh 2 "Forking During Queue Runs"
will fork before each individual message
from consuming large amounts of memory,
so it may be useful in memory-poor environments.
will keep track of hosts that are down during a queue run,
which can improve performance dramatically.
can not use connection caching.
Every message is assigned a priority when it is first instantiated,
consisting of the message size (in bytes)
offset by the message class times the
and the number of recipients times the
.q "work recipient factor."
The priority is used to order the queue.
Higher numbers for the priority mean that the message will be processed later
The message size is included so that large messages are penalized
relative to small messages.
The message class allows users to send
the value of this field is looked up in the
lines of the configuration file.
Since the number of recipients affects the amount of load a message presents
this is also included into the priority.
The recipient and class factors
can be set in the configuration file using the
They default to 30000 (for the recipient factor)
pri = size - (class times bold z) + (nrcpt times bold y)
(Remember, higher values for this parameter actually mean
that the job will be treated with lower priority.)
The priority of a job can also be adjusted each time it is processed
(that is, each time an attempt is made to deliver it)
This is added to the priority,
so it normally decreases the precedence of the job,
on the grounds that jobs that have failed many times
will tend to fail again in the future.
option defaults to 90000.
can be asked to queue (but not deliver)
mail if the system load average gets too high
When the load average exceeds the value of the
the delivery mode is set to
divided by the difference in the current load average and the
exceeds the priority of the message \(em
that is, the message is queued iff:
pri > { bold q } over { LA - { bold x } + 1 }
option defaults to 200000,
so each point of load average is worth 200000
option defines a load average at which
to accept network connections.
(including incoming UUCP mail)
There are a number of delivery modes that
specify how quickly mail will be delivered.
i deliver interactively (synchronously)
b deliver in background (asynchronously)
q queue only (don't deliver)
passes the maximum amount of information to the sender,
but is hardly ever necessary.
puts the minimum load on your machine,
but means that delivery may be delayed for up to the queue interval.
is probably a good compromise.
However, this mode can cause large numbers of processes
if you have a mailer that takes a long time to deliver a message.
will not expand aliases and follow .forward files
upon initial receipt of the mail.
This speeds up the response to RCPT commands.
The level of logging can be set for
The default using a standard configuration table is level 9.
The levels are as follows:
Serious system failures and potential security problems.
Lost communications (network problems) and protocol failures.
Message collection statistics.
Creation of error messages,
Delivery failures (host or user unknown, etc.).
(due to a host being down, etc.).
Database expansion (alias, forward, and userdb lookups).
Automatic alias database rebuilds.
Logs attempts to run locked queue files.
but can be useful to note if your queue appears to be clogged.
Lost locks (only if using lockf instead of flock).
values above 64 are reserved for extremely verbose debuggging output.
No normal site would ever set these.
There are a number of files
that may have a number of modes.
The modes depend on what functionality you want
and the level of security you require.
.sh 3 "To suid or not to suid?"
At the point where it is about to
it checks to see if the userid is zero;
it resets the userid and groupid to a default
for mailers that are trusted
and must be called as root.)
this will cause mail processing
rather than to the user sending the mail.
.sh 3 "Should my alias database be writable?"
we have the alias database
While this is not as flexible as if the database
were more 666, it avoids potential security problems
with a globally writable database.
is represented by the two files
if you are running with the new Berkeley database primitives).
The mode on these files should match the mode
users will be unable to reflect their desired changes
through to the actual database.
and the DBM files are writable,
a slightly sophisticated user
can arrange to steal mail anyway.
If your DBM files are not writable by the world
or you do not have auto-rebuild enabled
then you must be careful to reconstruct the alias database
each time you change the text version:
If this step is ignored or forgotten
any intended changes will also be ignored or forgotten.
.sh 2 "Connection Caching"
When processing the queue,
will try to keep the last few open connections open
to avoid startup and shutdown costs.
This only applies to IPC connections.
When trying to open a connection
the cache is first searched.
If an open connection is found, it is probed to see if it is still active
It is not an error if this fails;
instead, the connection is closed and reopened.
Two parameters control the connection cache.
option defines the number of simultaneous open connections
connections will be closed as quickly as possible.
This should be set as appropriate for your system size;
it will limit the amount of system resources that
will use during queue runs.
option specifies the maximum time that any cached connection
will be permitted to idle.
When the idle time exceeds this value
the connection is closed.
This number should be small
to prevent you from grabbing too many resources
The default is five minutes.
.sh 2 "Name Server Access"
If your system supports the name server,
then the probability is that
will be using it regardless of how you configure
In particular, the system routine
is used to look up host names,
and most vendor versions try some combination of DNS, NIS,
and file lookup in /etc/hosts.
However, if you do not have a nameserver configured at all,
such as at a UUCP-only site,
message when it tries to connect to the name server
(either indirectly by calling
or directly by looking up MX records).
will interpret this to mean a temporary failure
and will queue the mail for later processing;
otherwise, it ignores the name server data.
If your name server is running properly,
the setting of this option is not relevant;
however, it is important that it be set properly
to make error handling work properly.
This option also allows you to tweak name server options.
The command line takes a series of flags as documented in
Each can be preceded by an optional `+' or `\(mi'.
OITrue +AAONLY \(miDNSRCH
turns on the AAONLY (accept authoritative answers only)
and turns off the DNSRCH (search the domain path) options.
Most resolver libraries default DNSRCH, DEFNAMES, and RECURSE
flags on and all others off.
Note the use of the initial ``True'' \*-
this is for compatibility with previous versions of
but is not otherwise necessary.
Version level 1 configurations
turn DNSRCH and DEFNAMES off when doing delivery lookups,
but leave them on everywhere else.
ignores them when doing canonification lookups
(that is, when using $[ ... $]),
and always does the search.
If you don't want to do automatic name extension,
The search rules for $[ ... $] are somewhat different than usual.
If the name (that is, the ``...'')
has at least one dot, it always tries the unmodified name first.
If that fails, it tries the reduced search path,
and lastly tries the unmodified name
(but only for names without a dot,
since names with a dot have already been tried).
This allows names such as
to match the site in Czechoslovakia
rather than the site in your local Computer Science department.
It also prefers A and CNAME records over MX records \*-
that is, if it finds an MX record it makes note of it,
This way, if you have a wildcard MX record matching your domain,
it will not assume that all names match.
.sh 2 "Moving the Per-User Forward Files"
Some sites mount each user's home directory
from a local disk on their workstation,
so that local access is fast.
However, the result is that .forward file lookups are slow.
mail can even be delivered on machines inappropriately
because of a file server being down.
The performance can be especially bad if you run the automounter.
option allows you to set a path of forward files.
For example, the config file line
OJ/var/forward/$u:$z/.forward
would first look for a file with the same name as the user's login
if that is not found (or is inaccessible)
in the user's home directory is searched.
A truly perverse site could also search by sender
If you create a directory such as /var/forward,
(that is, the sticky bit should be set).
Users should create the files mode 644.
you can specify a minimum number of free blocks on the queue filesystem
If there are fewer than the indicated number of blocks free
on the filesystem on which the queue is mounted
the SMTP server will reject mail
This invites the SMTP client to try again later.
Beware of setting this option too high;
it can cause rejection of email
when that mail would be processed without difficulty.
This option can also specify an advertised
.q "maximum message size"
for hosts that speak ESMTP.
option allows you to set certain
Actually, many of them don't give you any extra privacy,
rather just insisting that client SMTP servers
before using certain commands.
The option takes a series of flag names;
the final privacy is the inclusive or of those flags.
insists that the HELO or EHLO command be used before a MAIL command is accepted
and disables the EXPN command.
option restricts printing the queue to the group that owns the queue directory.
It is absurd to set this if you don't also protect the logs.
option restricts people running the queue
to root and the owner of the queue directory.
deletes the (envelope) sender from any list expansions.
sends to a list that contains
as one of the members he won't get a copy of the message.
command line flag, or if the
option is set in the configuration file,
this behaviour is supressed.
Some sites like to run the
.sh 1 "THE WHOLE SCOOP ON THE CONFIGURATION FILE"
This section describes the configuration file
including hints on how to write one of your own
There is one point that should be made clear immediately:
the syntax of the configuration file
is designed to be reasonably easy to parse,
since this is done every time
rather than easy for a human to read or write.
configuration-file compiler.
An overview of the configuration file
followed by details of the semantics.
.sh 2 "Configuration File Lines"
The configuration file is organized as a series of lines,
each of which begins with a single character
defining the semantics for the rest of the line.
Lines beginning with a space or a tab
(although the semantics are not well defined in many places).
Blank lines and lines beginning with a sharp symbol
.sh 3 "R and S \*- rewriting rules"
The core of address parsing
These are an ordered production system.
scans through the set of rewriting rules
looking for a match on the left hand side
the address is replaced by the right hand side
There are several sets of rewriting rules.
Some of the rewriting sets are used internally
and must have specific semantics.
do not have specifically assigned semantics,
and may be referenced by the mailer definitions
or by other rewriting sets.
The syntax of these two commands are:
Sets the current ruleset being collected to
If you begin a ruleset more than once
it deletes the old definition.
by at least one tab character;
there may be embedded spaces
is a pattern that is applied to the input.
the input is rewritten to the
Macro expansions of the form
are performed when the configuration file is read.
are performed at run time using a somewhat less general algorithm.
This for is intended only for referencing internally defined macros
that are changed at runtime.
.sh 4 "The left hand side"
The left hand side of rewriting rules contains a pattern.
Normal words are simply matched directly.
Metasyntax is introduced using a dollar sign.
.ta \w'\fB$=\fP\fIx\fP 'u
\fB$*\fP Match zero or more tokens
\fB$+\fP Match one or more tokens
\fB$\-\fP Match exactly one token
\fB$=\fP\fIx\fP Match any phrase in class \fIx\fP
\fB$~\fP\fIx\fP Match any word not in class \fIx\fP
they are assigned to the symbol
for replacement on the right hand side,
the rule will match, and the values passed to the RHS will be:
Additionally, the LHS can include
on the RHS, and is normally only used when it stands alone
in order to match the null input.
.sh 4 "The right hand side"
When the left hand side of a rewriting rule matches,
the input is deleted and replaced by the right hand side.
Tokens are copied directly from the RHS
unless they begin with a dollar sign.
\fB$\fP\fIn\fP Substitute indefinite token \fIn\fP from LHS
\fB$[\fP\fIname\fP\fB$]\fP Canonicalize \fIname\fP
\fB$(\fP\fImap key\fP \fB$@\fP\fIarguments\fP \fB$:\fP\fIdefault\fP \fB$)\fP
Generalized keyed mapping function
\fB$>\fP\fIn\fP \*(lqCall\*(rq ruleset \fIn\fP
\fB$#\fP\fImailer\fP Resolve to \fImailer\fP
\fB$@\fP\fIhost\fP Specify \fIhost\fP
\fB$:\fP\fIuser\fP Specify \fIuser\fP
syntax substitutes the corresponding value from a
A host name enclosed between
routines and replaced by the canonical name\**.
to $(host \fIhostname\fP$).
.q vangogh.CS.Berkeley.EDU.
recognizes it's numeric IP address
without calling the name server
and replaces it with it's canonical name.
syntax is a more general form of lookup;
it uses a named map instead of an implicit map.
If no lookup is found, the indicted
if no default is specified and no lookup matches,
the value is left unchanged.
causes the remainder of the line to be substituted as usual
and then passed as the argument to ruleset
The final value of ruleset
the substitution for this rule.
or a subroutine of ruleset zero.
It causes evaluation of the ruleset to terminate immediately,
that the address has completely resolved.
\fB$#\fP\fImailer\fP \fB$@\fP\fIhost\fP \fB$:\fP\fIuser\fP
3-tuple necessary to direct the mailer.
the host part may be omitted\**.
\**You may want to use it for special
For example, at CMU you can send email to
the part after the plus sign
is not part of the user name,
and is passed to the local mailer for local use.
is the builtin IPC mailer,
may be a colon-separated list of hosts
that are searched in order for the first working address
(exactly like MX records).
A RHS may also be preceded by a
prefix causes the ruleset to return with the remainder of the RHS
prefix causes the rule to terminate immediately,
but the ruleset to continue;
this can be used to avoid continued application of a rule.
The prefix is stripped before continuing.
passes that to ruleset seven,
is necessary to avoid an infinite loop.
Substitution occurs in the order described,
parameters from the LHS are substituted,
hostnames are canonicalized,
.sh 4 "Semantics of rewriting rule sets"
There are five rewriting sets
that have specific semantics.
These are related as depicted by figure 2.
-->| 0 |-->resolved address
+---+ / +---+ / +---+ +---+ \e +---+
addr-->| 3 |-->| D |-- --->| 4 |-->msg
+---+ +---+ \e +---+ +---+ / +---+
BoxD: box "D"; line; L1: Here
C1: arrow; box "1"; arrow; box "S"; line; E1: Here
move to C1 down 0.5; right
C2: arrow; box "2"; arrow; box "R"; line; E2: Here
] with .w at L1 + (0.5, 0)
L4: arrow; box "4"; arrow; box invis "msg"
move to BoxD.n up 0.6; right
arrow; box invis "resolved address" width 1.3
line from 1/3 of the way between A1 and BoxD.w to Box0
Figure 2 \*- Rewriting set semantics
D \*- sender domain addition
S \*- mailer-specific sender rewriting
R \*- mailer-specific recipient rewriting
should turn the address into
This form should have the basic syntax:
local-part@host-domain-spec
flag is set in the mailer definition
before doing anything with any address.
is applied after ruleset three
to addresses that are going to actually specify recipients.
.i "{mailer, host, user}"
must be defined in the mailer definitions
from the configuration file.
for use in the argv expansion of the specified mailer.
are applied to all sender and recipient addresses respectively.
They are applied before any specification
in the mailer definition.
Ruleset four is applied to all addresses
to translate internal to external form.
Some special processing occurs
if the ruleset zero resolves to an IPC mailer
(that is, a mailer that has
listed as the Path in the
The host name passed after
has MX expansion performed;
this looks the name up in DNS to find alternate delivery sites.
The host name can also be provided as a dotted quad in square brackets;
This causes direct conversion of the numeric value
to a TCP/IP host address.
The host name passed in after the
may also be a colon-separated list of hosts.
Each is separately MX expanded and the results are concatenated
to make (essentially) one long MX list.
The intent here is to create
MX records that are not published in DNS
for private internal networks.
As a final special case, the host name can be passed in
This form avoids the MX mapping.
This is intended only for situations where you have a network firewall,
so that your MX record points to a gateway machine;
this machine could then do direct delivery to machines
within your local domain.
Use of this feature directly violates RFC 1123 section 5.3.5:
it should not be used lightly.
.sh 3 "D \*- define macro"
Macros are named with a single character.
These may be selected from the entire ASCII set,
should be selected from the set of upper case letters only.
The syntax for macro definitions is:
is the value it should have.
is the name of the macro to be interpolated.
This interpolation is done when the configuration file is read,
lines to get deferred interpolation.
Conditionals can be specified using the syntax:
Lower case macro names are reserved to have
used to pass information in or out of
and special characters are reserved to
provide conditionals, etc.
are specifically reserved for configuration file authors.
The following macros are defined and/or used internally by
for interpolation into argv's for mailers
The ones marked \(dg are information passed into sendmail\**,
all of these macros have reasonable defaults.
Previous versions required that they be defined.
the ones marked \(dd are information passed both in and out of sendmail,
and the unmarked macros are passed out of sendmail
but are not otherwise used internally.
.b "The origination date in RFC 822 format."
.b "The current date in RFC 822 format."
.b "The current date in UNIX (ctime) format."
.b "The SMTP entry message."
This is printed out when SMTP starts up.
The first word must be the
macro as specified by RFC821.
.q "$j Sendmail $v ready at $b" .
Commonly redefined to include the configuration version number, e.g.,
.q "$j Sendmail $v/$Z ready at $b"
.b "The sender (from) address."
.b "The sender address relative to the recipient."
.b "The \*(lqofficial\*(rq domain name for this site."
This is fully qualified if the full qualification can be found.
be redefined to be the fully qualified domain name
if your system is not configured so that information can find
.b "The UUCP node name (from the uname system call)."
.b "The format of the UNIX from line."
Unless you have changed the UNIX mailbox format,
you should not change the default,
.b "The domain part of the \fIgethostname\fP return value."
Under normal circumstances,
.b "The name of the daemon (for error messages)."
.b "The set of "operators" in addresses."
which will be considered tokens
and which will separate tokens
would be scanned as three tokens:
which is the minimum set necessary to do RFC 822 parsing;
a richer set of operators is
which adds support for UUCP, the %-hack, and X.400 addresses.
.b "Sendmail's process id."
.b "Default format of sender address."
macro specifies how an address should appear in a message
It is commonly redefined to be
corresponding to the following two formats:
Eric Allman <eric@CS.Berkeley.EDU>
eric@CS.Berkeley.EDU (Eric Allman)
properly quotes names that have special characters
if the first form is used.
.b "Protocol used to receive the message."
.b "A numeric representation of the current time."
.b "The version number of \fIsendmail\fP."
.b "The hostname of this site."
macro is set to the root name of this host (but see below for caveats).
.b "The full name of the sender."
.b "The home directory of the recipient."
.b "The validated sender address."
There are three types of dates that can be used.
macros are in RFC 822 format;
is the time as extracted from the
is the current date and time
line is found in the incoming message,
is set to the current time also.
macro is equivalent to the
are set to the identity of this host.
tries to find the fully qualified name of the host
to get the current hostname
which is supposed to return the canonical version of that host name.\**
\**For example, on some systems
Assuming this is successful,
is set to the fully qualified name
is set to the domain part of the name
(everything after the first dot).
macro is set to the first word
(everything before the first dot)
if you have a level 5 or higher configuration file;
otherwise, it is set to the same value as
If the canonification is not successful,
it is imperative that the config file set
to the fully qualified domain name\**.
\**Older versions of sendmail didn't pre-define
macro is the id of the sender
as originally determined;
when mailing to a specific host
macro is set to the address of the sender
relative to the recipient.
.q bollard@matisse.CS.Berkeley.EDU
.q vangogh.CS.Berkeley.EDU
.q eric@vangogh.CS.Berkeley.EDU.
macro is set to the full name of the sender.
This can be determined in several ways.
It can be passed as flag to
The second choice is the value of the
line in the header if it exists,
and the third choice is the comment field
and if the message is being originated locally,
the full name is looked up in the
macros get set to the host, user, and home directory
The first two are set from the
part of the rewriting rules, respectively.
macros are used to create unique strings
macro is set to the queue id on this host;
if put into the timestamp line
it can be extremely useful for tracking messages.
macro is set to be the version number of
this is normally put in timestamps
and has been proven extremely useful for debugging.
i.e., the number of times this message has been processed.
or by counting the timestamps in the message.
fields are set to the protocol used to communicate with
and the sending hostname.
is set to a validated sender host name.
If the sender is running an RFC 1413 compliant IDENT server,
it will include the user name on that host.
.sh 3 "C and F \*- define classes"
Classes of phrases may be defined
to match on the left hand side of rewriting rules,
is a sequence of characters that do not contain space characters.
a class of all local names for this site
so that attempts to send to oneself
These can either be defined directly in the configuration file
or read in from another file.
Classes may be given names
from the set of upper case letters.
Lower case letters and special characters
are reserved for system use.
The first form defines the class
to match any of the named words.
It is permissible to split them among multiple lines;
for example, the two forms:
reads the elements of the class
(match entries not in class)
only matches a single word;
multi-word entries in the class are ignored in this context.
is set to be the set of all names
This can be used to match local hostnames.
that is, the UUCP node name.
.sh 3 "M \*- define mailer"
Programs and interfaces to mailers
are defined in this line.
is the name of the mailer
pairs define attributes of the mailer.
Path The pathname of the mailer
Flags Special flags for this mailer
Sender A rewriting set for sender addresses
Recipient A rewriting set for recipient addresses
Argv An argument vector to pass to this mailer
Eol The end-of-line string for this mailer
Maxsize The maximum message length to this mailer
Linelimit The maximum line length in the message body
Directory The working directory for the mailer
Only the first character of the field name is checked.
The following flags may be set in the mailer description.
Any other flags may be used freely
to conditionally assign headers to messages
destined for particular mailers.
Run Extended SMTP (ESMTP) protocol (defined in RFCs 1425, 1426, and 1427).
Force a blank line on the end of a message.
This is intended to work around some stupid versions of
that require a blank line, but do not provide it themselves.
It would not normally be used on network mail.
Do not include comments in addresses.
This should only be used if you have to work around
a remote mailer that gets confused by comments.
from a mailer with this flag set,
any addresses in the header that do not have an at sign
after being rewritten by ruleset three
This allows mail with headers of the form:
To: userb@hostb, userc@hosta
This mailer is expensive to connect to,
so try to avoid connecting normally;
any necessary connection will occur during a queue run.
Escape lines beginning with
in the message with a `>' sign.
but only if this is a network forward operation
the mailer will give an error
does not have special permissions).
sends internally generated email (e.g., error messages)
using the null return address\**
\**Actually, this only applies to SMTP,
which uses the ``MAIL FROM:<>'' command.
However, some mailers don't accept a null return address.
from obeying the standards;
error messages will be sent as from the MAILER-DAEMON
(actually, the value of the
Upper case should be preserved in host names
This mailer will be speaking SMTP
as such it can use special protocol features.
This option is not required
if this option is omitted the transmission will still operate successfully,
although perhaps not as efficiently as possible).
final delivery will be performed).
Limit the line lengths as specified in RFC821.
This deprecated option should be replaced by the
For historic reasons, the
This mailer can send to multiple users
part of the mailer definition,
that field will be repeated as necessary
for all qualifying users.
Do not insert a UNIX-style
line on the front of the message.
Use the route-addr style reverse-path in the SMTP
rather than just the return address;
although this is required in RFC821 section 3.1,
many hosts do not process reverse-paths properly.
Reverse-paths are officially discouraged by RFC 1123.
Strip quote characters off of the address
before calling the mailer.
before calling the mailer.
This would be used in a secure environment
This could be used to avoid forged addresses.
This flag is suppressed if given from an
(e.g, a user's mail.cf file).
Upper case should be preserved in user names
This mailer wants Unix-style
lines with the ugly UUCP-style
This mailer want to use the hidden dot algorithm
any line beginning with a dot
will have an extra dot prepended
(to be stripped at the other end).
This insures that lines in the message containing a dot
will not terminate the message prematurely.
Strip all output to seven bits.
This is the default if the
Note that setting this is not
sufficient to get full eight bit data passed through
option is set, this is essentially always set,
since the eighth bit was stripped on input.
The mailer with the special name
can be used to generate a user error.
The (optional) host field is an exit status to be returned,
and the user field is a message to be printed.
The exit status may be numeric or one of the values
USAGE, NOUSER, NOHOST, UNAVAILABLE, SOFTWARE, TEMPFAIL, PROTOCOL, or CONFIG
to return the corresponding EX_ exit code.
$#error $@ NOHOST $: Host unknown in this domain
will cause the specified error to be generated
exit status to be returned
This mailer is only functional in ruleset zero.
be defined in every configuration file.
This is used to deliver local mail,
and is treated specially in several ways.
Additionally, three other mailers named
may be defined to tune the delivery of messages to programs,
and :include: lists respectively.
Mprog, P=/bin/sh, F=lsD, A=sh \-c $u
M*file*, P=/dev/null, F=lsDFMPEu, A=FILE
M*include*, P=/dev/null, F=su, A=INCLUDE
The Sender and Recipient rewriting sets
may either be a simple integer
or may be two integers separated by a slash;
if so, the first rewriting set is applied to envelope
and the second is applied to headers.
is actually a colon-separated path of directories to try.
For example, the definition
first tries to execute in the recipient's home directory;
if that is not available,
it tries to execute in the root of the filesystem.
This is intended to be used only on the
since some shells (such as
refuse to execute if they cannot read the home directory.
Since the queue directory is not normally readable by normal users
scripts as recipients can fail.
.sh 3 "H \*- define header"
The format of the header lines that
The syntax of this line is:
Continuation lines in this spec
are reflected directly into the outgoing message.
is macro expanded before insertion into the message.
(surrounded by question marks)
at least one of the specified flags
must be stated in the mailer definition
for this header to be automatically output.
If one of these headers is in the input
it is reflected to the output
regardless of these flags.
Some headers have special semantics
that will be described below.
can be set from a configuration file.
Options are represented by single characters.
The syntax of this line is:
may be a string, an integer,
The options supported are:
entry to exist in the alias database
.ip "A\fIspec, spec, ...\fP"
Specify possible alias file(s).
is optional and defaults to ``implicit''.
is compiled, valid classes are
(search through a compiled-in list of alias file types,
(internal symbol table \*- not normally used
unless you have no other database lookup),
blocks free on the filesystem that holds the queue files
before accepting email via SMTP.
If there is insufficient space
This invites the sender to try again later.
is a maximum message size advertised in the ESMTP EHLO response.
It is currently otherwise unused.
Set the blank substitution character to
Unquoted spaces in addresses are replaced by this character.
Defaults to space (i.e., no change is made).
If an outgoing mailer is marked as being expensive,
don't connect immediately.
This requires that queueing be compiled in,
since it will depend on a queue run process to
Checkpoints the queue every
If your system crashes during delivery to a large list,
this prevents retransmission to any but the last
i Deliver interactively (synchronously)
b Deliver in background (asynchronously)
q Just queue the message (deliver during queue run)
Defaults to ``b'' if no option is specified,
``i'' if it is specified but given no argument
(i.e., ``Od'' is equivalent to ``Odi'').
rebuild the alias database if necessary and possible.
If this option is not set,
will never rebuild the alias database
unless explicitly requested
Dispose of errors using mode
p Print error messages (default)
q No messages, just give exit status
w Write back errors (mail if user not logged in)
e Mail back errors and give zero exit stat always
Prepend error messages with the indicated message.
If it begins with a slash,
it is assumed to be the pathname of a file
containing a message (this is the recommended setting).
Otherwise, it is a literal message.
The error file might contain the name, email address, and/or phone number
of a local postmaster who could provide assistance
If the option is missing or null,
or if it names a file which does not exist or which is not readable,
lines at the front of headers.
Normally they are assumed redundant
The file mode for queue files.
The value can also be given as a symbolic group name.
Allow fuzzy matching on the GECOS field.
and the usual user name lookups fail
(that is, there is no alias with this name and a
sequentially search the password file
for a matching entry in the GECOS field.
This also requires that MATCHGECOS
be turned on during compilation.
This option is not recommended.
Messages that have been processed more than
times are assumed to be in a loop and are rejected.
Ignore dots in incoming messages.
This is always disabled (that is, dots are always accepted)
Insist that the BIND name server be running
If this is not set and the name server is not running,
file will be considered complete.
In general, you do want to set this option
file does not include all hosts known to you
or if you are using the MX (mail forwarding) feature of the BIND name server.
The name server will still be consulted
even if this option is not set, but
will feel free to resort to reading
if the name server is not available.
set this option if you do not run the name server.
If set, send error messages in MIME format
(see RFC1341 and RFC1344 for details).
Set the path for searching for users' .forward files.
Some sites that use the automounter may prefer to change this to
to search a file with the same name as the user in a system directory.
It can also be set to a sequence of paths separated by colons;
stops at the first file it can successfully and safely open.
.q /var/forward/$u:$z/.forward
will search first in /var/forward/\c
(but only if the first file does not exist).
The maximum number of open connections that will be cached at a time.
This delays closing the the current connection until
either this invocation of
needs to connect to another host
Setting it to zero defaults to the old behavior,
that is, connections are closed immediately.
The maximum amount of time a cached connection will be permitted to idle
If this time is exceeded,
the connection is immediately closed.
This value should be small (on the order of ten minutes).
uses a cached connection,
it always sends a NOOP (no operation) command
if this fails, it reopens the connection.
This keeps your end from failing if the other end times out.
The point of this option is to be a good network neighbor
and avoid using up excessive resources
The default is five minutes.
header, send error messages to the addresses listed there.
They normally go to the envelope sender.
Use of this option causes
Set the default log level to
even if I am in an alias expansion.
This is intended only for use from the command line.
Validate the RHS of aliases when rebuilding the alias database.
Assume that the headers may be in old format,
if any recipient address contains a comma, parenthesis,
it will be assumed that commas already exist.
only commas delimit names.
Headers are always output with commas between the names.
Port Name/number of listening port (defaults to "smtp")
Addr Address mask (defaults INADDR_ANY)
Family Address family (defaults to INET)
Listen Size of listen queue (defaults to 10)
mask may be a numeric address in dot notation
``Privacy'' is really a misnomer;
many of these are just a way of insisting on stricter adherence
needmailhelo Insist on HELO or EHLO command before MAIL
needexpnhelo Insist on HELO or EHLO command before EXPN
noexpn Disallow EXPN entirely
needvrfyhelo Insist on HELO or EHLO command before VRFY
novrfy Disallow VRFY entirely
restrictmailq Restrict mailq command
restrictqrun Restrict \-q command line flag
goaway Disallow essentially all SMTP status queries
pseudo-flag sets all flags except
only people in the same group as the queue directory
If queue runs are restricted,
only root and the owner of the queue directory
copies of error messages will be sent to the named
Only the header of the failed message is sent.
Since most errors are user problems,
this is probably not a good idea on large sites,
and arguably contains all sorts of privacy violations,
but it seems to be popular with certain operating systems vendors.
as the multiplier in the map function
to decide when to just queue up jobs rather than run them.
This value is divided by the difference between the current load average
and the load average limit
to determine the maximum message priority
The recognized timeouts and their default values, and their
minimum values specified in RFC 1123 section 5.3.2 are:
initial wait for initial greeting message [5m, 5m]
helo reply to HELO or EHLO command [5m, none]
mail reply to MAIL command [10m, 5m]
rcpt reply to RCPT command [1h, 5m]
datainit reply to DATA command [5m, 2m]
datablock data block read [1h, 3m]
datafinal reply to final ``.'' in data [1h, 10m]
rset reply to RSET command [5m, none]
quit reply to QUIT command [2m, none]
misc reply to NOOP and VERB commands [2m, none]
command command read [1h, 5m]
ident IDENT protocol timeout [30s, none]
a timeout with no ``keyword='' part
will set all of the longer values.
tries to eliminate any unnecessary explicit routes
when sending an error message
(as discussed in RFC 1123 \(sc 5.2.6).
when sending an error message to
<@known1,@known2,@unknown:user@known3>
in order to make the route as direct as possible.
option is set, this will be disabled,
and the mail will be sent to the first address in the route,
even if later addresses are known.
This may be useful if you are caught behind a firewall.
Be super-safe when running things,
always instantiate the queue file,
even if you are going to attempt immediate delivery.
always instantiates the queue file
before returning control the the client
Log statistics in the named
Set the local time zone info to
Actually, if this is not set,
the TZ environment variable is cleared (so the system default is used);
if set but null, the user's TZ variable is used,
and if set and non-null the TZ variable is set to this value.
messages that have not been successfully sent
will be returned to the sender.
is the time after which a warning message is sent.
then no warning messages are sent.
Set the default userid for mailers to
flag in the mailer definition
The value can also be given as a symbolic user name.
The user database specification.
(don't connect to expensive mailers)
so that all mail is delivered completely
so that you can see the entire delivery process.
be set in the configuration file;
it is intended for command line use only.
acts like a very low priority MX
This is intended to be used by sites with poor network connectivity.
(that is, lowest preference)
you should normally detect this situation
and treat that condition specially,
by forwarding the mail to a UUCP feed,
However, in some cases (such as Internet firewalls)
you may want to try to connect directly to that host
as though it had no MX records at all.
Setting this option causes
The downside is that errors in your configuration
are likely to be diagnosed as
instead of something more meaningful.
This option is disrecommended.
When the system load average exceeds
(i.e., don't try to send them).
When the system load average exceeds
refuse incoming SMTP connections.
is added to the priority (thus
i.e., this value penalizes jobs with large numbers of recipients.
deliver each job that is run from the queue in a separate process.
Use this option if you are short of memory,
since the default tends to consume considerable amounts of memory
while the queue is being processed.
is multiplied by the message class
(determined by the Precedence: field in the user header
lines in the configuration file)
and subtracted from the priority.
Thus, messages with a higher Priority: will be favored.
every time a job is processed.
each time a job is processed,
its priority will be decreased by the indicated value.
In most environments this should be positive,
since hosts that are down are all too often down for a long time.
Strip input to seven bits for compatibility with old systems.
This shouldn't be necessary.
All options can be specified on the command line using the
to relinquish its setuid permissions.
The options that will not cause this are
b, d, e, E, i, L, m, o, p, r, s, v, C, and 7.
Also, M (define macro) when defining the r or s macros
.sh 3 "P \*- precedence definitions"
field may be defined using the
The syntax of this field is:
\fBP\fP\fIname\fP\fB=\fP\fInum\fP
the message class is set to
Higher numbers mean higher precedence.
have the special property
that if an error occurs during processing
the body of the message will not be returned;
this is expected to be used for
mail such as through mailing lists.
The default precedence is zero.
our list of precedences is:
People writing mailing list exploders
(which discarded all error returns for negative precedences)
didn't recognize this name, giving it a default precedence of zero.
This allows list maintainers to see error returns
on both old and new versions of
.sh 3 "V \*- configuration version level"
To provide compatibility with old configuration files,
line has been added to define some very basic semantics
of the configuration file.
These are not intended to be long term supports;
rather, they describe compatibility features
which will probably be removed in future releases.
used version level 5 configurations.
configuration files are defined as version level one.
Version level two files make the following changes:
Host name canonification ($[ ... $])
appends a dot if the name is recognized;
this gives the config file a way of finding out if anything matched.
(Actually, this just initializes the
flag \*- you can reset it to anything you prefer
by declaring the map explicitly.)
Default host name extension is consistent throughout processing;
version level one configurations turned off domain extension
(that is, adding the local domain name)
during certain points in processing.
Version level two configurations are expected to include a trailing dot
to indicate that the name is already canonical.
Local names that are not aliases
are passed through a new distinguished ruleset five;
this can be used to append a local relay.
This behaviour can be prevented by resolving the local name
That is, something that resolves to a local mailer and a user name of
will be passed through ruleset five,
will have the `@' stripped,
will not be passed through ruleset five,
but will otherwise be treated the same as the prior example.
The expectation is that this might be used to implement a policy
was handled by a central hub,
Version level three files
allow # initiated comments on all lines.
Exceptions are backslash escaped # marks
Version level four configurations
are completely equivalent to level three
Version level five configuration files
change the default definition of
to be just the first component of the hostname.
.sh 3 "K \*- key file declaration"
Special maps can be defined using the line:
Kmapname mapclass arguments
is the handle by which this map is referenced in the rewriting rules.
is the name of a type of map;
are interpreted depending on the class;
there would be a single argument naming the file containing the map.
Maps are referenced using the syntax:
$( \fImap\fP \fIkey\fP $@ \fIarguments\fP $: \fIdefault\fP $)
where either or both of the
may appear more than once.
are passed to the appropriate mapping function.
If it returns a value, it replaces the input.
If it does not return a value and the
Otherwise, the input is unchanged.
During replacement of either a map value or default
is replaced by the corresponding
is always the database key.
R$- ! $+ $: $(uucp $1 $@ $2 $: %1 @ %0 . UUCP $)
Looks up the UUCP name in a (user defined) UUCP map;
if not found it turns it into
The database might contain records like:
The built in map with both name and class
is the host name canonicalization lookup.
There are four predefined database lookup classes:
the second two require the
and the third requires that
be compiled with NIS support.
All four accept as arguments the some optional flags
the filename is the root of the database path,
or some other extension appropriate for the database type
will be added to get the actual database name).
Indicates that this map is optional \*- that is,
will behave as if the map existed but was empty.
Normally when maps are written,
the trailing null byte is not included as part of the key.
If this flag is indicated it will be included.
During lookups, only the null-byte-included form will be searched.
uses an adaptive algorithm to decide whether or not to look for null bytes
It starts by trying both;
if it finds any key with a null byte it never tries again without a null byte
If this flag is specified,
it never tries with a null byte;
this can speed matches but is never necessary.
will never try any matches at all \(em
that is, everything will appear to fail.
map appends a dot on successful matches.
Fold upper to lower case before looking up the key.
Match only (without replacing the value).
If you only care about the existence of a key and not the value
(as you might when searching the NIS map
this flag prevents the map from substituting the value.
The \-a argument is still appended on a match,
and the default is still taken if the match fails.
For example, the map specification
Kuucp dbm \-o \-N /usr/lib/uucpmap
specifies an optional map named
it always has null bytes at the end of every string,
and the data is located in
/usr/lib/uucpmap.{dir,pag}.
can be used to build any of the three database-oriented maps.
It takes the following flags:
Do not fold upper to lower case in the map.
Include null bytes in keys.
Append to an existing (old) file.
Allow replacement of existing keys;
normally, re-inserting an existing key is an error.
daemon does not have to be restarted to read the new maps
as long as you change them in place;
file locking is used so that the maps won't be read
while they are being updated.\**
\**That is, don't create new maps and then use
I consider this a shortfall (a.k.a. bug) in
which should be fixed in a future release.
There are also two builtin maps that are,
map does host domain canonification;
given a host name it calls the name server
to find the canonical name for that host.
map strips double quotes (") from a name.
It does not strip backslashes.
It will not strip quotes if the resulting string
would contain unscannable syntax
(that is, basic errors like unbalanced angle brackets;
more sophisticated errors such as unknown hosts are not checked).
The intent is for use when trying to accept mail from systems such as
that routinely quote odd syntax such as
A typical usage is probably something like:
Care must be taken to prevent unexpected results;
"|someprogram < input > output"
will have quotes stripped,
but the result is probably not what you had in mind.
Fortunately these cases are rare.
New classes can be added in the routine
.sh 2 "Building a Configuration File From Scratch"
Building a configuration table from scratch is an extremely difficult job.
it is almost never necessary to do so;
nearly every situation that may come up
may be resolved by changing an existing table.
it is critical that you understand what it is that you are trying to do
and come up with a philosophy for the configuration table.
This section is intended to explain what the real purpose
of a configuration table is
and to give you some ideas
for what your philosophy might be.
.b "Do not even consider"
writing your own configuration file
without carefully studying
You should also read RFC 976
if you are doing UUCP exchange.
.sh 3 "What you are trying to do"
The configuration table has three major purposes.
is to set up the environment for
This involves setting the options,
defining a few critical macros,
Since these are described in other places,
we will not go into more detail here.
The second purpose is to rewrite addresses in the message.
This should typically be done in two phases.
The first phase maps addresses in any format
This should be done in ruleset three.
The second phase maps this canonical form
into the syntax appropriate for the receiving mailer.
does this in three subphases.
are applied to all sender and recipient addresses respectively.
you may specify per-mailer rulesets
for both sender and recipient addresses;
this allows mailer-specific customization.
ruleset four is applied to do any default conversion
is to map addresses into the actual set of instructions
necessary to get the message delivered.
Ruleset zero must resolve to the internal form,
which is in turn used as a pointer to a mailer descriptor.
The mailer descriptor describes the interface requirements
The particular philosophy you choose will depend heavily
on the size and structure of your organization.
I will present a few possible philosophies here.
There are as many philosophies as there are config designers;
feel free to develop your own.
One general point applies to all of these philosophies:
it is almost always a mistake
to try to do full host route resolution.
if you are on a UUCP-only site
and you are trying to get names of the form
it does not pay to route them to
.q xyzvax!decvax!ucbvax!c70!user@host
since you then depend on several links not under your control,
some of which are likely to misparse it anyway.
The best approach to this problem
is to simply forward the message for
worry about it from there.
just get the message closer to the destination,
rather than determining the full path.
.sh 4 "Large site, many hosts \*- minimum information"
Berkeley is an example of a large site,
i.e., more than two or three hosts
and multiple mail connections.
We have decided that the only reasonable philosophy
is to designate one host as the guru for our site.
It must be able to resolve any piece of mail it receives.
The other sites should have the minimum amount of information
any information they do have
should be hints rather than solid information.
a typical site on our local ether network is
.q monet.CS.Berkeley.EDU ).
When monet receives mail for delivery,
it checks whether it knows
that the destination host is directly reachable;
if so, mail is sent to that host.
If it receives mail for any unknown host,
it just passes it directly to
.q ucbvax.CS.Berkeley.EDU ,
Ucbvax may determine that the host name is illegal
or may be able to do delivery.
However, it is important to note that when a new mail connection is added,
be updated if convenient,
but this is not critical.
This picture is slightly muddied
due to network connections that are not actually located
some UUCP connections are currently on
the information is hidden totally between ucbvax and ucbarpa.
Mail going from monet to a UUCP host
is transferred via the ethernet
then via the ethernet from ucbvax to ucbarpa,
and then is submitted to UUCP.
Although this involves some extra hops,
we feel this is an acceptable tradeoff.
An interesting point is that it would be possible
to send appropriate UUCP mail directly to ucbarpa
if the load got too high;
if monet failed to note a host as connected to ucbarpa
it would go via ucbvax as before,
and if monet incorrectly sent a message to ucbarpa
it would still be sent by ucbarpa
The only problem that can occur is loops,
if ucbarpa thought that ucbvax had the UUCP connection
happen to the master host first.
This philosophy results as much from the need
to have a single source for the configuration files
Maintaining more than three separate tables by hand
is essentially an impossible job.
.sh 4 "Small site \*- complete information"
(two or three hosts and few external connections)
may find it more reasonable to have complete information
This would require that each host
know exactly where each network connection is,
possibly including the names of each host on that network.
As long as the site remains small
and the the configuration remains relatively static,
the update problem will probably not be too great.
This is in some sense the trivial case.
The only major issue is trying to insure that you don't
have to know too much about your environment.
if you have a UUCP connection
you might find it useful to know about the names of hosts
connected directly to you,
but this is really not necessary
since this may be determined from the syntax.
.sh 4 "A completely different philosophy"
This is adapted from Bruce Lilly.
Any errors in interpretation are mine.
Do minimal changes in ruleset 3:
fix some common but unambiguous errors (e.g. trailing dot on domains) and
hide bang paths foo!bar into bar@foo.UUCP.
The resulting "canonical" form is any valid RFC822/RFC1123/RFC976 address.
Ruleset 0 does the bulk of the work.
It removes the trailing "@.UUCP" that hides bang paths,
strips anything not needed to resolve,
e.g. the phrase from phrase <route-addr> and from named groups,
rejects unparseable addresses using $#error,
resolves to a mailer/host/user triple.
Ruleset 0 is rather lengthy
as it has to handle 3 basic address forms:
(including vanilla RFC822 local-part@domain),
and RFC822 source routes.
It's also complicated by having to handle named lists.
The header rewriting rulesets 1 and 2
remove the trailing "@.UUCP" that hides bang paths.
Ruleset 2 also strips the $# mailer $@ host (for test mode).
Ruleset 4 does absolutely nothing.
The per-mailer rewriting rulesets conform the envelope and
header addresses to the requirements of the specific
Lots of rulesets-as-subroutines are used.
As a result, header addresses are subject to minimal munging
(per RFC1123), and the general plan is per RFC822 sect. 3.4.10.
The canonical form you use
should almost certainly be as specified in
Copies of these RFC's are included on the
describes the format of the mail message itself.
follows this RFC closely,
to the extent that many of the standards described in this document
can not be changed without changing the code.
the following characters have special interpretations:
Any attempt to use these characters for other than their RFC822
purpose in addresses is probably doomed to disaster.
describes the specifics of the domain-based addressing.
This is touched on in RFC822 as well.
Essentially each host is given a name
which is a right-to-left dot qualified pseudo-path
from a distinguished root.
The elements of the path need not be physical hosts;
the domain is logical rather than physical.
reading from right to left,
comprising educational institutions,
is a logical domain name,
represents the Computer Center,
(in this case a strictly logical entity),
is a host in the Computer Center.
Beware when reading RFC819
that there are a number of errors in it.
Once you have decided on a philosophy,
it is worth examining the available configuration tables
to decide if any of them are close enough
Even under the worst of conditions,
there is a fair amount of boiler plate that can be collected safely.
The next step is to build ruleset three.
This will be the hardest part of the job.
Beware of doing too much to the address in this ruleset,
since anything you do will reflect through
stripping of local domains is best deferred,
since this can leave you with addresses with no domain spec at all.
likes to append the sending domain to addresses with no domain,
this can change the semantics of addresses.
fully qualifying domains in this ruleset.
Although technically legal,
this can lead to unpleasantly and unnecessarily long addresses
The Berkeley configuration files
to qualify domain names and strip local domains.
This is called from ruleset zero
to get all addresses into a cleaner form.
Once you have ruleset three finished,
the other rulesets should be relatively trivial.
examine the supplied configuration tables.
.sh 3 "Testing the rewriting rules \*- the \-bt flag"
When you build a configuration table,
you can do a certain amount of testing
which would read the configuration file
you enter lines of the form:
is the rewriting set you want to use
is an address to apply the set to.
Test mode shows you the steps it takes
finally showing you the address it ends up with.
You may use a comma separated list of rwsets
for sequential application of rules to an input.
first applies ruleset three to the input
Ruleset one is then applied to the output of ruleset three,
followed similarly by rulesets twenty-one and four.
flag to turn on more debugging.
turns on an incredible amount of information;
is probably going to print out several pages worth of information.
You should be warned that internally,
applies ruleset 3 to all addresses.
you will have to do that manually.
For example, older versions allowed you to use
0 bruce@broadcast.sony.com
This version requires that you use:
3,0 bruce@broadcast.sony.com
.sh 3 "Building mailer descriptions"
To add an outgoing mailer to your mail system,
you will have to define the characteristics of the mailer.
Each mailer must have an internal name.
The pathname of the mailer must be given in the P field.
If this mailer should be accessed via an IPC connection,
The F field defines the mailer flags.
flag to pass the name of the sender as a
These flags are only passed if they were passed to
so that mailers that give errors under some circumstances
If the mailer is not picky
If the mailer must be called as
this will not reset the userid
before calling the mailer\**.
must be running setuid to root
(i.e., will perform final delivery
rather than another network hop)
(backslashes and " marks)
can be stripped from addresses if the
If the mailer is capable of sending to more than one user
then the argv template containing
will be repeated for each unique user
flag will mark the mailer as being
configuration option must be given
for this to be effective.
This flag applies to the mailer that the message is received from,
rather than the mailer being sent to;
the domain spec of the sender
and is appended to any addresses in the message
that do not already contain a domain spec.
From: eric@vangogh.CS.Berkeley.EDU
To: wnj@monet.CS.Berkeley.EDU, mckusick
From: eric@vangogh.CS.Berkeley.EDU
To: wnj@monet.CS.Berkeley.EDU, mckusick@vangogh.CS.Berkeley.EDU
flag is defined in the mailer corresponding to
.q eric@vangogh.CS.Berkeley.EDU.
Other flags are described
The S and R fields in the mailer description
are per-mailer rewriting sets
to be applied to sender and recipient addresses
These are applied after the sending domain is appended
and the general rewriting sets
but before the output rewrite
A typical use is to append the current domain
to addresses that do not already have a domain.
From: eric@vangogh.CS.Berkeley.EDU
depending on the domain it is being shipped into.
These sets can also be used
to do special purpose output rewriting
in cooperation with ruleset four.
can be specified as two numbers separated by a slash
meaning that all envelope addresses will be processed through ruleset 10
and all header addresses will be processed through ruleset 11.
With only one number specified,
both envelope and header rewriting sets are set to the indicated ruleset.
The E field defines the string to use
as an end-of-line indication.
A string containing only newline is the default.
The usual backslash escapes
an argv template is given as the E field.
It may have embedded spaces.
If there is no argv with a
If the pathname for this mailer is
is the optional port number
.ta \w'Mlocal, 'u +\w'P=/bin/mail, 'u +\w'F=rlsm, 'u +\w'S=10, 'u +\w'R=20, 'u
Mlocal, P=/bin/mail, F=rlsm S=10, R=20, A=mail \-d $u
Mether, P=[IPC], F=meC, S=11, R=21, A=IPC $h, M=100000
specifies a mailer to do local delivery
and a mailer for ethernet delivery.
quotes should be stripped from addresses,
and multiple users can be delivered at once;
should be applied to sender addresses in the message
should be applied to recipient addresses;
the argv to send to a message will be the word
and words containing the name of the receiving user.
it will be between the words
The second mailer is called
it should be connected to via an IPC connection,
it can handle multiple users at once,
connections should be deferred,
and any domain from the sender address
should be appended to any receiver name
sender addresses should be processed by ruleset eleven
and recipient addresses by ruleset twenty-one.
There is a 100,000 byte limit on messages passed through this mailer.
.sh 2 "The User Database"
with the user database package
the handling of sender and recipient addresses
The location of this database is controlled with the
.sh 3 "Structure of the user database"
The database is a sorted (BTree-based) structure.
User records are stored with the key:
\fIuser-name\fP\fB:\fP\fIfield-name\fP
The sorted database format ensures that user records are clustered together.
Meta-information is always stored with a leading colon.
Field names define both the syntax and semantics of the value.
The delivery address for this user.
There may be multiple values of this record.
mailing lists will have one
record for each user on the list.
The outgoing mailname for this user.
there should be an appropriate
record for that name to allow return mail.
Changes any mail sent to this address to have the indicated envelope sender.
This is intended for mailing lists,
and will normally be the name of an appropriate -request address.
It is very similar to the owner-\c
syntax in the alias file.
The full name of the user.
The office address for this user.
The office phone number for this user.
The office FAX number for this user.
The home address for this user.
The home phone number for this user.
The home FAX number for this user.
A (short) description of the project this person is affiliated with.
In the University this is often just the name of their graduate advisor.
A pointer to a file from which plan information can be gathered.
only a few of these fields are actually being used by
program that uses the other fields is planned.
.sh 3 "User database semantics"
When the rewriting rules submit an address to the local mailer,
the user name is passed through the alias file.
If no alias is found (or if the alias points back to the same address),
is then used as a key in the user database.
If no match occurs (or if the maildrop points at the same address),
If the first token of the user name returned by ruleset 0
sign, the user database lookup is skipped.
The intent is that the user database will act as a set of defaults
for a cluster (in our case, the Computer Science Division);
mail sent to a specific machine should ignore these defaults.
the name of the sending user is looked up in the database.
the value of that record is used as their outgoing name.
For example, I might have a record:
eric:mailname Eric.Allman@CS.Berkeley.EDU
This would cause my outgoing mail to be sent as Eric.Allman.
If present, this is the name of a host to override the local host.
For example, in our case we would set it to
The effect is that anyone known in the database
gets their outgoing mail stamped as
.q user@CS.Berkeley.EDU ,
but people not listed in the database use the local hostname.
.sh 1 "OTHER CONFIGURATION"
There are some configuration changes that can be made by
This section describes what changes can be made
and what has to be modified to make them.
.sh 2 "Parameters in src/Makefile"
These parameters are intended to describe the compilation environment,
and should normally be defined in src/Makefile.
the new version of the DBM library
that allows multiple databases will be used.
If neither NDBM nor NEWDB are set,
a much less efficient method of alias lookup is used.
If set, use the new database package from Berkeley (from 4.4BSD).
This package is substantially faster than DBM or NDBM.
If NEWDB and NDBM are both set,
but will create and use NEWDB files.
will create both DBM and NEWDB files if and only if
the file /var/yp/Makefile
This is intended for compatibility with Sun Microsystems'
program used on YP masters.
Set all of the compilation parameters appropriate for System V.
Due to the highly unusual semantics of locks
this should never be used unless absolutely necessary.
Set this if your system has the
(if you have multiple group support).
This is the default if SYSTEM5 is
defined or if you are on HPUX.
system call (or corresponding library routine).
This will allow you to give a temporary failure
message to incoming SMTP email
when you are low on disk space.
It is set by default on 4.4BSD and OSF/1 systems.
This is an alternative implementation of disk space control.
You should only set one of HASSTATFS or HASUSTAT;
The pathname of the sendmail.cf file.
The pathname of the sendmail.pid file.
Details are described below.
The are four built-in ways of computing the load average.
tries to auto-configure them based on imperfect guesses;
you can select one using the
The kernel stores the load average in the kernel as an array of long integers.
The actual values are scaled by a factor FSCALE
The kernel stores the load average in the kernel as an array of short integers.
The actual values are scaled by a factor FSCALE
The kernel stores the load average in the kernel as an array of
routine to get the load average as an array of doubles.
Always return zero as the load average.
This is the fallback case.
you may also need to specify
(the path to your system binary)
(the name of the variable containing the load average in the kernel;
There are also several compilation flags to indicate the environment
file for the latest scoop on these flags.
.sh 2 "Parameters in src/conf.h"
Parameters and compilation options
Most of these need not normally be tweaked;
common parameters are all in sendmail.cf.
However, the sizes of certain primitive vectors, etc.,
are included in this file.
The numbers following the parameters
The maximum line length of any input line.
If message lines exceed this length
they will still be processed correctly;
configuration file lines,
must fit within this limit.
The maximum length of any name,
such as a host or a user name.
The maximum number of parameters to any mailer.
This limits the number of recipients that may be passed in one transaction.
It can be set to any arbitrary number above about 10,
will break up a delivery into smaller batches as needed.
A higher number may reduce load on your system, however.
The maximum number of atoms
.q "eric@CS.Berkeley.EDU"
The maximum number of mailers that may be defined
in the configuration file.
The maximum number of rewriting sets
The maximum number of values for the
field that may be defined
.ip "MAXUSERENVIRON [40]"
The maximum number of items in the user environment
that will be passed to subordinate mailers.
The maximum number of entries that will be processed
The maximum number of MX records we will accept for any single host.
A number of other compilation options exist.
These specify whether or not specific code should be compiled in.
If set, debugging information is compiled in.
To actually get the debugging output,
.b "WE STRONGLY RECOMMEND THAT THIS BE LEFT ON."
Some people, believing that it was a security hole
have turned it off and thus crippled debuggers.
support for Internet protocol networking is compiled in.
this old usage is now incorrect.
support for ISO protocol networking is compiled in
(it may be appropriate to #define this in the Makefile instead of conf.h).
routine in use at some sites is used.
This makes an informational log record
for each message processed,
and makes a higher priority log record
for internal system errors.
Compile in the code to do ``fuzzy matching'' on the GECOS field
This also requires that option G be turned on.
Compile in code to use the
Berkeley Internet Name Domain (BIND) server
to resolve TCP/IP host names.
If you are using a non-UNIX mail format,
you can set this flag to turn off special processing
This flag should be set to compile in the queueing code.
mailers must accept the mail immediately
or it will be returned to the sender.
array to indicate its current status.
This can be used in conjunction with the
command to find out just what it's up to.
the code to handle user and server SMTP will be compiled in.
This is only necessary if your machine has some mailer
(this means most machines everywhere).
If you have a UUCP host adjacent to you which is not running
you will have to set this flag to include the
Otherwise, UUCP gets confused about where the mail came from.
Berkeley user information database package.
This adds a new level of local name expansion
between aliasing and forwarding.
It also uses the NEWDB package.
This may change in future releases.
Compile in the IDENT protocol as defined in RFC 1413.
This defaults on for all systems except Ultrix,
which apparently has the interesting
message it closes all open connections to that host.
Since some firewall gateways send this error code
when you access an unauthorized port (such as 113, used by IDENT),
Ultrix cannot receive email from such hosts.
.sh 2 "Configuration in src/conf.c"
The following changes can be made in conf.c.
.sh 3 "Built-in Header Semantics"
Not all header semantics are defined in the configuration file.
Header lines that should only be included by certain mailers
(as well as other more obscure semantics)
This table contains the header name
(which should be in all lower case)
and a set of header control flags (described below),
Normally when the check is made to see if a header line is compatible
will not delete an existing line.
even existing header lines.
if this bit is set and the mailer does not have flag bits set
that intersect with the required mailer flags
in the header definition in
If this header field is set,
treat it like a blank line,
it will signal the end of the header
and the beginning of the message text.
even if one existed in the message before.
If a header entry does not have this bit set,
will not add another header line if a header line
of this name already existed.
This would normally be used to stamp the message
by everyone who handled it.
If the number of trace fields in a message
on the assumption that it has an aliasing loop.
this field contains recipient addresses.
flag to determine who to send to
when it is collecting recipients from the message.
This flag indicates that this field
The order of these fields in the
for which field to return error messages to.
.ta 4n +\w'"return-receipt-to", 'u
struct hdrinfo HdrInfo[] =
/* originator fields, most to least significant */
/* message identification and control */
"received", H_TRACE|H_FORCE,
This structure indicates that the
all specify recipient addresses.
field will be deleted unless the required mailer flag
(indicated in the configuration file)
fields will terminate the header;
these are used by random dissenters around the network world.
field will always be added,
and can be used to trace messages.
There are a number of important points here.
header fields are not added automatically just because they are in the
they must be specified in the configuration file
in order to be added to the message.
Any header fields mentioned in the configuration file but not
structure have default processing performed;
they are added unless they were in the message already.
structure only specifies cliched processing;
certain headers are processed specially by ad hoc code
regardless of the status specified in
fields are always scanned on ARPANET mail
to determine the sender\**;
\**Actually, this is no longer true in SMTP;
this information is contained in the envelope.
The older ARPANET protocols did not completely distinguish
this is used to perform the
fields are used to determine the full name of the sender
this is stored in the macro
and used in a number of ways.
.sh 3 "Restricting Use of Email"
If it is necessary to restrict mail through a relay,
This routine is called for every recipient address.
It returns an exit status
indicating the status of the message.
queues the message for a later try,
to print an error message
if the message is rejected.
.ta 4n +4n +4n +4n +4n +4n +4n
s = stab("private", ST_MAILER, ST_FIND);
if (s != NULL && e\->e_from.q_mailer != LocalMailer &&
to->q_mailer == s->s_mailer)
usrerr("No private net mail allowed through this machine");
if (MsgSize > 50000 && to\->q_mailer != LocalMailer)
usrerr("Message too large for non-local delivery");
This would reject messages greater than 50000 bytes
flag can be sent to suppress the return of the actual body
of the message in the error return.
The actual use of this routine is highly dependent on the
and use should be limited.
.sh 3 "Load Average Computation"
should return an approximation of the current system load average
There are four versions included on compilation flags
.sh 3 "New Database Map Classes"
New key maps can be added by creating a class initialization function
These are then added to the routine
The initialization function is called as
\fIxxx\fP_map_init(MAP *map, char *mapname, char *args)
is an internal data structure.
is the name of the map (used for error messages).
is a pointer to the rest of the configuration file line;
flags and filenames can be extracted from this line.
The initialization function must return
if it successfully opened the map,
The lookup function is called as
\fIxxx\fP_map_lookup(MAP *map, char buf[], int bufsize, char **av, int *statp)
defines the map internally.
This may be (and often is) used destructively.
is a list of arguments passed in from the rewrite line.
The lookup function should return a pointer to the new value.
should be set to an exit status code;
in particular, it should be set to
if recovery is to be attempted by the higher level code.
.sh 3 "Queueing Function"
is called to decide if a message should be queued
or processed immediately.
Typically this compares the message priority to the current load average.
The default definition is:
if (CurrentLA >= RefuseLA)
return (pri > (QueueFactor / (CurrentLA \- QueueLA + 1)));
If the current load average
which is set before this function is called)
is less than the low threshold load average
If the current load average exceeds the high threshold load average
Otherwise, it computes the function based on the message priority,
and the current and threshold load averages.
An implementation wishing to take the actual age of the message into account
which is the time that the message was first submitted to
parameter is already weighted
by the number of times the message has been tried
(although this tends to lower the priority of the message with time);
the expectation is that the
to ensure that messages are eventually processed.
.sh 3 "Refusing Incoming SMTP Connections"
if incoming SMTP connections should be refused.
The current implementation is based exclusively on the current load average
and the refuse load average option
return (CurrentLA >= RefuseLA);
A more clever implementation
could look at more system resources.
.sh 3 "Load Average Computation"
returns the current load average (as a rounded integer).
The distribution includes several possible implementations.
.sh 2 "Configuration in src/daemon.c"
contains a number of routines that are dependent
on the local networking environment.
The version supplied assumes you have BSD style sockets.
we recommended that you modify the routine
if you wanted to generalize
We now recommend that you create a new keyed map instead.
.sh 1 "CHANGES IN VERSION 8"
The following summarizes changes
since the last commonly available version of
.sh 2 "Connection Caching"
Instead of closing SMTP connections immediately,
those connections are cached for possible future use.
The advent of MX records made this effective for mailing lists;
substantial performance improvements can be expected for queue processing.
If two hosts with different names in a single message
happen to have the same set of MX hosts,
they can be sent in the same transaction.
Version 8 notices this and tries to batch the messages.
.sh 2 "RFC 1123 Compliance"
A number of changes have been made to make
.q "conditionally compliant"
clauses and most but not all of the
The major areas of change are (numbers are RFC 1123 section numbers):
Response to RCPT command is fast.
Numeric IP addresses are logged in Received: lines.
Self domain literal is properly handled.
Better control over individual timeouts.
Error messages are sent as
Error messages are never sent to
.q "unconditionally compliant"
doesn't always use the exact SMTP message text
doesn't guarantee only one connect for each host in queue runs.
doesn't always provide adequate concurrency limits.
.sh 2 "Extended SMTP Support"
Version 8 includes both sending and receiving support for Extended
SMTP support as defined by RFC 1425 (basic) and RFC 1427 (SIZE);
and limited support for RFC 1426 (BODY).
used the 0200 bit for quoting.
This version avoids that use.
However, for compatibility with RFC 822,
you can set option `7' to get seven bit stripping.
Individual mailers can still produce seven bit out put using the
The user database is an as-yet experimental attempt
to provide unified large-site name support.
We are installing it at Berkeley;
future versions may show significant modifications.
.sh 2 "Improved BIND Support"
particularly for MX records,
which have been removed in this release.
these more tightly bind (pun intended) the name server to
so that the name server resolution rules are incorporated directly into
Generalized keyed files is an idea taken directly from
(albeit with a completely different implementation).
They can be useful on large sites.
Version 8 also understands YP.
.sh 2 "Multi-Word Classes"
Classes can now be multiple words.
CShofmann.CS.Berkeley.EDU
allows you to match the entire string
.q hofmann.CS.Berkeley.EDU
using the single construct
.sh 2 "Deferred Macro Expansion"
construct has been adopted from
.sh 2 "IDENT Protocol Support"
The IDENT protocol as defined in RFC 1413 is supported.
.sh 2 "Parsing Bug Fixes"
A number of small bugs having to do with things like
backslash-escaped quotes inside of comments
.sh 2 "Separate Envelope/Header Processing"
Since the From: line is passed in separately from the envelope sender,
these have both been made visible;
macro is set to the envelope sender during processing
of mailer argument vectors
and the header sender during processing of headers.
It is also possible to specify separate per-mailer
envelope and header processing.
to give different rewritings for envelope versus header addresses.
.sh 2 "Owner-List Propagates to Envelope"
When an alias has an associated owner\-list name,
that alias is used to change the envelope sender address.
This will cause downstream errors to be returned to that owner.
.sh 2 "Dynamic Header Allocation"
The fixed size limit on header lines has been eliminated.
.sh 2 "New Command Line Flags"
flag has been added to pass in body type information.
to pass in protocol information.
to allow logging of all protocol in and out of
.sh 2 "Enhanced Command Line Flags"
flag can limit limit a queue run to specific recipients, senders, or queue ids
.sh 2 "New and Old Configuration Line Types"
(Trusted users) configuration line has been deleted.
It will still be accepted but will be ignored.
line has been added to declare database maps.
line has been added to declare the configuration version level.
field that lets you change into a temporary directory while that mailer
Several new options have been added,
many to support new features,
others to allow tuning that was previously available
They are described in detail in Section 5.1.5.
Insist on a minimum number of disk blocks.
Send errors in MIME-encapsulated format.
Connection cache lifetime.
Enable Errors-To: header.
These headers violate RFC 1123;
this option is included to provide back compatibility
Set incoming SMTP daemon options, such as an alternate SMTP port.
Do not run eight bit clean.
options have been extended to pass in more information.
Several new mailer flags have been added.
Try to use ESMTP when creating a connection.
will still try if the other end hints that it knows about ESMTP
this flag says to try even if it doesn't hint.
If the EHLO (extended hello)
Ensure that there is a blank line at the end of all messages.
Strip all comments from addresses;
this should only be used as a last resort
when dealing with cranky mailers.
Never use the null sender as the envelope sender,
Although this violates RFC 1123,
it may be necessary when you must deal with some obnoxious old hosts.
Strip all output to 7 bits.
.sh 2 "New Pre-Defined Macros"
The following macros are pre-defined:
The domain part of our full hostname.
The RFC 1413-provided sender address.
on the Left Hand Side of an
line to match zero tokens.
This is intended to be used to match the null input.
Version 8 allows up to 100 rulesets instead of 30.
It is recommended that rulesets 0\-9 be reserved for
dedicated use in future releases.
The total number of MX records that can be used has been raised to 20.
The number of queued messages that can be handled at one time
has been raised from 600 to 1000.
.sh 2 "Different Default Tuning Parameters"
Version 8 has changed the default parameters
to make the number of recipients more important
than the size of the message (for small messages).
This is reasonable if you are connected with reasonably fast links.
.sh 2 "Auto-Quoting in Addresses"
.q "Full Name <email address>"
syntax would generate incorrect protocol output
had special characters such as dot.
This version puts quotes around such names.
.sh 2 "Symbolic Names On Error Mailer"
Several names have been built in to the $@ portion of the $#error
.sh 2 "SMTP VRFY Doesn't Expand"
treated VRFY and EXPN the same.
VRFY doesn't expand aliases or follow .forward files.
As an optimization, if you run with your default delivery mode being
the RCPT command will also not chase aliases and .forward files.
It will chase them when it processes the queue.
.sh 2 "[IPC] Mailers Allow Multiple Hosts"
When an address resolves to a mailer that has
can be a colon-separated list of hosts instead of a single hostname.
to search the list for the first entry that is available
exactly as though it were an MX record.
The intent is to route internal traffic through internal networks
without publishing an MX record to the net.
MX expansion is still done on the individual items.
The implementation has been merged with maps.
this supports NIS-based aliases.
.sh 2 "Portability and Security Enhancements"
A number of internal changes have been made to enhance portability.
Several fixes have been made to increase the paranoia factor.
.sh 2 "Miscellaneous Changes"
file with the current process id of the SMTP daemon.
Two people using the same program in their .forward file
so that duplicate elimination doesn't delete one of them.
program prints mailer names
and gets the location of the
Many minor bugs have been fixed, such as handling of backslashes
A hook (ruleset 5) has been added
to allow rewriting of local addresses after aliasing.
and many employers have been remarkably patient
about letting me work on a large project
that was not part of my official job.
This includes time on the INGRES Project at Berkeley,
and again on the Mammoth Project at Berkeley.
Much of the second wave of improvements
should be credited to Bryan Costales of ICSI.
As he passed me drafts of his book on
I was inspired to start working on things again.
Bryan was also available to bounce ideas off of.
Many, many people contributed chunks of code and ideas to
It has proven to be a group network effort.
Version 8 in particular was a group project.
The following people made notable contributions:
Keith Bostic, CSRG, University of California, Berkeley
Michael J. Corrigan, University of California, San Diego
Bryan Costales, International Computer Science Institute
Pa\*:r (Pell) Emanuelsson
Craig Everhart, Transarc Corporation
Tom Ivar Helbekkmo, Norwegian School of Economics
Jonathan Kamens, OpenVision Technologies, Inc.
Takahiro Kanbe, Fuji Xerox Information Systems Co., Ltd.
Brian Kantor, University of California, San Diego
Murray S. Kucherawy, HookUp Communication Corp.
Nakamura Motonori, Kyoto University
John Gardiner Myers, Carnegie Mellon University
Neil Rickert, Northern Illinois University
Eric Schnoebelen, Convex Computer Corp.
Eric Wassenaar, National Institute for Nuclear and High Energy Physics, Amsterdam
Christophe Wolfhugel, Herve Schauer Consultants (Paris)
I apologize for anyone I have omitted, misspelled, misattributed, or
Many other people have contributed ideas, comments, and encouragement.
I appreciate their contribution as well.
Arguments must be presented with flags before addresses.
s Speak SMTP on input side
v Just verify addresses, don't collect or deliver
i Initialize the alias database
Use a different configuration file.
runs as the invoking user (rather than root)
when this flag is specified.
The sender's machine address is
Sets the full name of this user to
This represents the number of times this message has been processed
(to the extent that it is supported by the underlying networks).
is incremented during processing,
throws away the message with an error.
Don't do aliasing or forwarding.
These options are described in Appendix B.
Set the sending protocol.
Programs are encouraged to set this.
The protocol field can be in the form
to set both the sending protocol and sending host.
sets the sending protocol to UUCP
and the sending host to uunet.
(Some existing programs use \-oM to set the r and s macros;
this is equivalent to using \-p.)
Try to process the queued up mail.
will run through the queue at the specified interval
otherwise, it only runs once.
limiting the jobs to those matching
to limit based on queue identifier,
to limit based on recipient,
to limit based on sender.
A particular queued job is accepted if one of the corresponding addresses
lines, and send to everyone listed in those lists.
line will be deleted before sending.
Any addresses in the argument vector will be deleted
Log all traffic in and out of
for debugging mailer problems.
This produces a lot of data very quickly and should be used sparingly.
There are a number of options that may be specified as
(provided for compatibility with
These are the e, i, m, and v options.
This appendix describes the format of the queue files.
These files live in the directory defined by the
All queue files have the name
\fIx\fP\|\fBf\fP\fIAAA99999\fP
The first letter of the id encodes the hour of the day
that the message was received by the system
(with A being the hour between midnight and 1:00AM).
All files with the same id collectively define one message.
The message body (excluding the header) is kept in this file.
the job is currently being processed,
and a queue run will not process the file.
file can cause a job to apparently disappear
(it will not even time out!).
[Actually, this file is obsolete on most systems that support the
This file is created when an id is being created.
It is a separate file to insure that no mail can ever be destroyed
It should exist for no more than a few milliseconds
[This is only used on old versions of
This file contains the information necessary to process the job.
These are an image of the
file when it is being rebuilt.
It should be renamed to a
existing during the life of a session
showing everything that happens
file is structured as a series of lines
each beginning with a code letter.
The lines are as follows:
The name of the data file.
There may only be one of these lines.
There may be any number of these lines.
they represent the order in the final message.
These use the same syntax
as header definitions in the configuration file.
Recipient addresses following this line
will be flagged so that deliveries will be run as the
(a user name from the /etc/passwd file);
is the name of the alias that expanded to this address
(used for printing messages).
This will normally be completely aliased,
but is actually realiased when the job is processed.
There may only be one of these lines.
they represent the addresses that should receive error messages.
This is used to compute when to time out the job.
The current message priority.
This is used to order the queue.
Higher numbers mean lower priorities.
as the message sits in the queue.
The initial priority depends on the message class
and the size of the message.
This line is printed by the
and is generally used to store status information.
Flag bits, represented as one letter per flag.
indicating that this is a response message
indicating that a warning message has been sent
announcing that the mail has been delayed.
The values of certain macros
(as of this writing, only
are passed through to the queue run phase.
The remainder of the line is a text string defining the body type.
If this field is missing,
the body type is assumed to be
and no special processing is attempted.
the following is a queue file sent to
.q eric@mammoth.Berkeley.EDU
.q bostic@okeeffe.CS.Berkeley.EDU \**:
\**This example is contrived and probably inaccurate for your environment.
Glance over it to get an idea;
nothing can replace looking at what your own system generates.
Eowner-sendmail@vangogh.CS.Berkeley.EDU
Ceric:sendmail@vangogh.CS.Berkeley.EDU
Reric@mammoth.Berkeley.EDU
Rbostic@okeeffe.CS.Berkeley.EDU
H?P?return-path: <owner-sendmail@vangogh.CS.Berkeley.EDU>
Hreceived: by vangogh.CS.Berkeley.EDU (5.108/2.7) id AAA06703;
Fri, 17 Jul 92 00:28:55 -0700
Hreceived: from mail.CS.Berkeley.EDU by vangogh.CS.Berkeley.EDU (5.108/2.7)
id AAA06698; Fri, 17 Jul 92 00:28:54 -0700
Hreceived: from [128.32.31.21] by mail.CS.Berkeley.EDU (5.96/2.5)
id AA22777; Fri, 17 Jul 92 03:29:14 -0400
Hreceived: by foo.bar.baz.de (5.57/Ultrix3.0-C)
id AA22757; Fri, 17 Jul 92 09:31:25 GMT
H?F?from: eric@foo.bar.baz.de (Eric Allman)
H?x?full-name: Eric Allman
Hmessage-id: <9207170931.AA22757@foo.bar.baz.de>
HTo: sendmail@vangogh.CS.Berkeley.EDU
Hsubject: this is an example message
This shows the name of the data file,
the person who sent the message,
(in seconds since January 1, 1970),
and the headers for the message.
.+c "SUMMARY OF SUPPORT FILES"
This is a summary of the support files
Many of these can be changed by editing the sendmail.cf file;
check there to find the actual pathnames.
.ip "/usr/\*(SD/sendmail"
.ip /usr/\*(SB/newaliases
A link to /usr/\*(SD/sendmail;
causes the alias database to be rebuilt.
Running this program is completely equivalent to giving
Prints a listing of the mail queue.
This program is equivalent to using the
A statistics file; need not be present.
it contains the process id of the current SMTP daemon.
If you use this in scripts;
use ``head \-1'' to get just the first line;
may add information to subsequent lines.
The textual version of the alias file.
.ip /etc/aliases.{pag,dir}
The directory in which the mail queue
and temporary files reside.
.ip /var/spool/mqueue/qf*
Control (queue) files for messages.
.ip /var/spool/mqueue/df*
.ip /var/spool/mqueue/tf*
Temporary versions of the qf files,
used during queue file rebuild.
.ip /var/spool/mqueue/xf*
A transcript of the current session.
.\"INSTALLATION AND OPERATION GUIDE
.\" remove some things to avoid "out of temp file space" problem
projects / unix-history / blob