distribute - reforward incoming messages to a mailing list

Distribute takes as its standard input a mail message, modifies
the header (and optionally the body) of that message, then invokes
sendmail to send the message to the specified recipients. It is
primarily useful for those who run large mailing lists.

Distribute does not include membership management.  It only does the
rewrite and dispatch of the mailng list emails.
Use majordomo (ports/mail/majordomo) for membership management.

Facilities include:
	Article numbering
	Subject rewrite to Subject: (mailing-list 1234)
	Proper handling of error related headers
	Reply-to rewrite/insertion if necessery
	Archiving
	membership file from Majordomo's configuration directory
