** (Someday) collect all names that are local in advance, and send
	them all off to /bin/mail at once -- fork before sending so
	that we can return status quickly.

    *** Handle :Include: specifications.

      * (Somehow) have "From" person modified so that if an alias exists
	for the person, it will appear post-aliased rather than pre-aliased,
	especially (perhaps only?) in ARPANET mail.  For example, if there
	exists an alias "fabry->cory:fabry", then if mail comes in from
	"cory:fabry", make it appear as though it were from "fabry".

      * Do aliasing on mail being returned also (?).

   **** Allow "<user>" "at" "<host>" as three separate parameters.

    *** Put host aliasing into the users file, e.g.,
	vax135!:research!vax135!

  ***** Change sendto & aliasdbm to know about quoted commas.
	Currently, quoted commas delimit aliases when they should be
	ignored.