qpsmtpd

qpsmtpd is a flexible smtpd daemon written in Perl. Apart from the core SMTP features, all functionality is implemented in small "extension plugins" using the easy to use object oriented plugin API.

qpsmtpd was originally written as a drop-in qmail-smtpd replacement, but now it also includes smtp forward, postfix, exim and maildir "backends".

Articles and Documentation

• The qpsmtpd wiki
• Using Qpsmtpd by Matt Sergeant (O'Reilly Network article)
• 5 minute lightning talk
• Using qpsmtpd for traps.SpamAssassin.org

Features

Plugins

• Advanced but simple to use plugin system to easily install extra functionality and write local rules.
• Almost all features are implemented in plugins
• For example: tls (implements STARTTLS), spamassassin, plugins for most major anti-virus programs, various AUTH plugins (ldap, vpopmail, ...), OS detection, queue plugins (qmail, exim, postfix, Maildir), greylisting, SPF, etc etc.
• Plugin directories: current development repository, Peter J. Holzer, Gavin Carr.

MTA compatibility

• Drop-in replacement for qmail-smtpd
• Postfix protocol module
• EXIM-BSMTP
• SMTP queuing plugin to support any SMTP compliant backend
• Other "backends" are easily implemented with a queue plugin

Anti-Spam

• Innovative spam fighting ideas can easily be implemented and tested with qpsmtpd plugins. One successful examples is the check_earlytalker plugin (disconnects most viruses and many spam engines before we even say hello!).
• Support for DNS Black Lists like the Spamhaus lists.
• Support for Domain-Based Blacklist Zones lists.
• Support for Milter filters (yes, those written for sendmail) with the milter plugin
• Greylisting with Gavin Carr's denysoft_greylist plugin
• DomainKeys support with the domainkeys plugin
• Integrated support for SpamAssassin
• Virus scanning with ClamAV
• Many others ...

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