All this does is push the question off a level. Is it desirable to be able
to mix and match MTA, delivery agent, and submission agent?
qmail was designed to support multiple delivery agents and submission
agents. qmail-local can invoke a variety of delivery agents. Submission
agents can run as /usr/lib/sendmail and pass messages to qmail-queue.
sendmail can also invoke a variety of delivery agents, and it'd be easy
to write a qmail-queue clone for sendmail if there were any interest.
When a delivery agent supports subaddresses---as, e.g., procmail does---
both qmail and (recent versions of) sendmail can straightforwardly pass
the necessary information to it.
Set up a new mailing list in a single command. http://pobox.com/~djb/ezmlm.html