Postmaster is an Internet mail transport
agent (MTA) that handles incoming ESMTP
network connections and delivers accepted
messages to the user's mailbox by piping it
into an arbitrary local mailer (such as
Procmail). It is configurable beyond anything
you'll ever need, handles any number of
concurrent connections without forking or
using OS threading, and it is pretty efficient. It
currently lacks any form of queue
management, but for leaf sites that don't
need to do extensive mail relaying, it is a
reliable and powerful solution.
