This is sendmail version 8.6.3.

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	SUMMARY OF CHANGES BETWEEN SENDMAIL V5 and V8

The following is a summary of the changes between the last commonly
available version of sendmail from Berkeley (5.67) and the latest
version (8.6).  I can't guarantee that it is complete.

Many of these are ideas that had been tried in IDA, albeit many of
them with a more general syntax.


Connection Caching

   Instead of closing SMTP connections immediately, open connections are
   cached for possible future use.  There is a limit to the number of
   simultaneous open connections and the idle time of any individual
   connection.
   
   This is of best help during queue processing (since there is the
   potential of many different messages going to one site), although
   it can also help when processing MX records which aren't handled
   by MX Piggybacking.

MX Piggybacking

   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.

   For example, if two sites ``foo.com'' and ``bar.com'' are both
   served by UUNET, they will have the same set of MX hosts and will
   be sent in one transaction.  UUNET will then split the message
   and send it to the two individual hosts.

RFC 1123 Changes

   A number of changes have been made to make sendmail ``conditionally
   compliant'' (that is, it satisfies all of the MUST clauses and most
   but not all of the SHOULD clauses in RFC 1123).

   The major areas of change are (numbers are RFC 1123 section numbers):

   5.2.7	Response to RCPT command is fast.  Previously, sendmail
		expanded all aliases as far as it could -- this could
		take a very long time, particularly if there were
		name server delays.  Version 8 only checks for the
		existence of an alias and does the expansion later.
   5.2.8	Numeric IP addresses are logged in Received: lines.
		This helps tracing spoofed messages.
   5.2.17	Self domain literal is properly handled.  Previously,
		if someone sent to user@[a.b.c.d], where a.b.c.d is
		your IP address, the mail would probably be rejected.
		Version 8 special cases these addresses.
   5.3.2	Better control over individual timeouts.  RFC 821 specified
		no timeouts.  Older versions of sendmail had a single
		timeout, typically set to two hours.  Version 8 allows
		the configuration file to set timeouts for various
		SMTP commands individually.
   5.3.3	Error messages are sent as From:<>.  This was urged by
		RFC 821 and reiterated by RFC 1123, but older versions
		of sendmail never really did it properly.  Version 8
		does.  However, some systems cannot handle this
		perfectly legal address; if necessary, you can create
		a special mailer that uses the `g' flag to disable this.
   5.3.3	Error messages are never sent to <>.  Previously,
		sendmail was happy to send responses-to-responses which
		sometimes resulted in responses-to-responses-to-responses
		which resulted in ....  you get the idea.
   5.3.3	Route-addrs (the ugly ``<@hosta,@hostb:user@hostc>''
		syntax) are pruned.  RFC 821 urged the use of this
		bletcherous syntax.  RFC 1123 has seen the light and
		officially deprecates them, further urging that you
		eliminate all but ``user@hostc'' should you receive
		one of these things.  Version 8 is slightly more generous
		than the standards suggest; instead of stripping off all
		the route addressees, it only strips hosts off up to
		the one before the last one known to DNS, thus allowing
		you to have pseudo-hosts such as foo.BITNET.  The 'R'
		option will turn this off.

   The areas in which sendmail is not ``unconditionally compliant'' are:

   5.2.6	Sendmail does do header munging.
   5.2.10	Sendmail doesn't always use the exact SMTP message
		text from RFC 821.  This is a rather silly requirement.
   5.3.1.1	Sendmail doesn't guarantee only one connect for each
		host on queue runs.  Connection caching gives you most
		of this, but it does not provide a guarantee.
   5.3.1.1	Sendmail doesn't always provide an adequate limit
		on concurrency.  That is, there can be several
		independent sendmails running at once.  My feeling
		is that doing an absolute limit would be a mistake
		(it might result in lost mail).  However, if you use
		the XLA contributed software, most of this will be
		guaranteed (but I don't guarantee the guarantee).

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).

Eight-Bit Clean

   Previous versions of sendmail 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
   `7' mailer flag.

User Database

   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.

   The user database allows you to map both incoming and outgoing
   addresses, much like IDA.  However, the interface set is still
   better with IDA.

Improved BIND Support

   The BIND support, particularly for MX records, had a number of
   annoying ``features'' which have been removed in this release.  In
   particular, these more tightly bind (pun intended) the name server
   to sendmail, so that the name server resolution rules are incorporated
   directly into sendmail.

   The major change has been that the $[ ... $] operator didn't fully
   qualify names that were in DNS as A or MX records.  Version 8 does
   this qualification.

Keyed Files

   Generalized keyed files is an idea taken directly from IDA sendmail
   (albeit with a completely different implementation).  They can be
   useful on large sites.

   Version 8 includes an "NIS" map class to support NIS/YP maps.

Multi-Word Classes

   Classes can now be multiple words.  For example,

	CShofmann.CS.Berkeley.EDU

   allows you to match the entire string ``hofmann.CS.Berkeley.EDU''
   using the single construct ``$=S''.

Deferred Macro Expansion

   The $&x construct has been adopted from IDA.

IDENT Protocol Support

   The IDENT protocol as defined in RFC 1413 is supported.

Parsing Bug Fixes

   A number of small bugs having to do with things like backslash-escaped
   quotes inside of comments have been fixed.

Separate Envelope/Header Processing

   Since the From: line is passed in separately from the envelope
   sender, these have both been made visible; the $g 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.  The SenderRWSet and RecipientRWset arguments
   for mailers can be specified as ``envelope/header'' to give different
   rewritings for envelope versus header addresses.

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.

Dynamic Header Allocation

   The fixed size limit on header lines has been eliminated.

New Command Line Flags

   The -B flag has been added to pass in body type information.

   The -p flag has been added to pass in protocol information.

   The -X flag has been added to allow logging of all protocol in and
   out of sendmail for debugging.

Enhanced Command Line Flags

   The -q flag can limit limit a queue run to specific recipients,
   senders, or queue ids using -qRsubstring, -qSsubstring, or
   -qIsubstring respectively.

New and Old Configuration Line Types

   The `T' (Trusted users) configuration line has been deleted.  It
   will still be accepted but will be ignored.

   The `K' line has been added to declare database maps.

   The `V' line has been added to declare the configuration version
   level.

   The `M' (mailer) line takes a D= field to specify execution
   directory.

New Options

   Several new options have been added, many to support new features,
   others to allow tuning that was previously available only by
   recompiling.  Briefly:

   b	Insist on a minimum number of disk blocks.

   C	Delivery checkpoint interval.  Checkpoint the queue (to avoid
	duplicate deliveries) every C addresses.

   E	Default error message.  This message (or the contents of the
	indicated file) are prepended to error messages.

   G	Enable GECOS matching.  If you can't find a local user name
	and this option is enabled, do a sequential scan of the passwd
	file to match against full names.  Previously a compile option.

   h	Maximum hop count.  Previously this was compiled in.

   j	Send errors in MIME-encapsulated format.

   J	Forward file path.  Where to search for .forward files -- defaults
	to $HOME/.forward.

   k	Connection cache size.  The total number of connections that will
	be kept open at any time.

   K	Connection cache lifetime.  The amount of time any connection
	will be permitted to sit idle.

   l	Enable Errors-To: header.  These headers violate RFC 1123;
  	this option is included to provide back compatibility with
	old versions of sendmail.

   O	Incoming daemon options (e.g., use alternate SMTP port).

   p	Privacy options.  These can be used to make your SMTP server
	less friendly.

   R	Don't prune route-addrs.  Normally, if version 8 sees an address
	like "<@hostA,@hostB:user@hostC>, sendmail will try to strip off
	as much as it can (up to user@hostC) as suggested by RFC 1123.
	This option disables that behaviour.

   U	User database spec.  This is still experimental.

   V	Fallback ``MX'' host.  This can be thought of as an MX host
	that applies to all addresses that has a very high preference
	value (that is, use it only if everything else fails).

   w	If set, assume that if you are the best MX host for a host,
	you should send directly to that host.  This is intended
	for compatibility with UIUC sendmail, and may have some
	use on firewalls.

   7	Do not run eight bit clean.  Technically, you have to assert
	this option to be RFC 821 compatible.

Extended Options

   The `r' (read timeout), `I' (use BIND), and `T' (queue timeout)
   options have been extended to pass in more information.

   The `A' (alias file) option has been extended to allow multiple
   alias files of different types.

New Mailer Flags

   a	Try to use ESMTP.  It will fall back to SMTP if the initial
  	EHLO packet is rejected.

   b	Ensure a blank line at the end of messages.  Useful on the
	*file* mailer.

   c	Strip all comments from addresses; this should only be used as
  	a last resort when dealing with cranky mailers.

   g	Never use the null sender as the envelope sender, even when
	running SMTP.  This violates RFC 1123.

   7	Strip all output to this mailer to 7 bits.

New Pre-Defined Macros

   $k	UUCP node name from uname(2).

   $m	Domain part of our full hostname.

   $_	RFC 1413-provided sender address.

New LHS Token

   Version 8 allows `$@' on the Left Hand Side of an `R' line to match
   zero tokens.  This is intended to be used to match the null input.

Bigger Defaults

   Version 8 allows up to 100 rulesets instead of 30.  It is recommended
   that rulesets 0-9 be reserved for sendmail's 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.

Different Default Tuning Parameters

   Version 8 has changed the default parameters for tuning queue costs
   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.

Auto-Quoting in Addresses

   Previously, the ``Full Name <email address>'' syntax would generate
   incorrect protocol output if ``Full Name'' had special characters
   such as dot.  This version puts quotes around such names.

Symbolic Names On Error Mailer

   Several names have been built in to the $@ portion of the $#error
   mailer.  For example:

	$#error $@NOHOST $: Host unknown

New Built-In Mailers

   Two new mailers, *file* and *include*, are included to define options
   when mailing to a file or a :include: file respectively.  Previously
   these were overloaded on the local mailer.

SMTP VRFY Doesn't Expand

   Previous versions of sendmail treated VRFY and EXPN the same.  In
   this version, VRFY doesn't expand aliases or follow .forward files.

   As an optimization, if you run with your default delivery mode
   being queue-only, the RCPT command will also not chase aliases and
   .forward files.  It will chase them when it processes the queue.
   This speeds up RCPT processing.

[IPC] Mailers Allow Multiple Hosts

   When an address resolves to a mailer that has ``[IPC]'' as its
   ``Path'', the $@ part (host name) can be a colon-separated list of
   hosts instead of a single hostname.  This asks sendmail 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.

Aliases Extended

   The implementation has been merged with maps.  Among other things,
   this supports multiple alias files and NIS-based aliases.  For
   example:

	OA/etc/aliases,nis:mail.aliases

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.

Miscellaneous Enhancements

   Sendmail writes a /etc/sendmail.pid file with the current process id
   and the current invocation flags.

   Two people using the same program (e.g., submit) are considered
   "different" so that duplicate elimination doesn't delete one of
   them.  For example, two people forwarding their email to
   |submit will be treated as two recipients.

   The mailstats program prints mailer names and gets the location of
   the sendmail.st file from /etc/sendmail.cf.

   Many minor bugs have been fixed, such as handling of backslashes
   inside of quotes.

   A hook has been added to allow rewriting of local addresses after
   aliasing.