(Version 4.1 of 7/25/83)

-- get rid of MAXMAILERS, just allocate them as you go; merge the stats
	structure in with the MAILERS structure; change the longs in
	said structure into u_longs; print the file in ASCII, lock the
	file before reading/printing.

-- clean up sysexits; get rid of EX_BASE, most of sysexits.c is duplicated
	in deliver.c

-- mailq; split it out, by default, just # of messages, also add sort
	by machine?

 ******	Finish properly implementing SMTP:
	- check correct name in HELO exchange (?)

  ***** Add an accounting package.  [acct.c]

  *****	When processing the queue, batch messages on the basis of
	receiving host rather than message -- so that if connections
	are expensive to complete, we get the most for our money.
	Unfortunately, this is a major change, and will probably
	wait for the next version.

   ****	Put in some more performance hooks.

    *** Integrate a null name server for future hackers.  [names.c]

    *** Have "Operating System Error" give more info (e.g.,
	"cannot fork").  [It really seems like this is ok now -- but
	this is an old delivermail gripe -- check it out more?]

     ** Per-mailer timeouts.  Invalidates old .cf files.

     ** Be able to generate a "response" (edit headers, etc.)
	given a message to respond to.

      * Have VRFY act as a limited name server (?).

      * Implement SEND and related commands in SMTP.

      * Extend full name matching.  This should actually be done in a
	complete name server.  Should the name server be integrated
	into sendmail (via a portal?) or should I "assume" that it
	has been called by the time I am called?
