May 26, 2018
Flexible SMTP daemon written in Perl and featuring a plugin API
Qpsmtpd started as a replacement daemon for the SMTP receiver qmail-smtpd from the qmail mail transport agent MTA. qmail-smtpd has a number of shortcomings e.g. being unable to check the validity of a recipient mail address and is written in C which makes it burdensome to modify and extend. Qpsmtpd, on the other hand, is written in pure perl and can be customized easily. It consists of a core that implements a complete SMTP server, and a number of plugins/modules which control the operations. Such plugins include plugins to check the recipient and sender as well as plugins for virus scanning, spam checking, blocking lists dns and rhs, AUTH and TLS. Qpsmtpd can not only be used with qmail but also with e.g. postfix and exim. It can also write messages to a Maildir or forward it to a remote host without buffering.