simple efficient SMTP proxy in perl

 smtpprox is a trivial transparent SMTP proxy, an SMTP server and client
 combination.
 .
 The SMTP server writes the incoming message to a temporary file, which the
 SMTP client reads as the message to send. SMTP commands and replies are
 relayed without change for the most part.
 .
 For efficiency reasons, it pre-forks and serves from a pool of servers,
 Apache-style.