PostMaster Express provides below plugins:

AvAc- the anti-virus application that integrates with PostMaster to scan all incoming, outgoing and internal mail.

GatePass- the antispam solution that combines multiple antispam methodologies in a layered sequence using a spam detection engine to provide world-class spam detection results.

SurfConsole- the proxy server that provides internet browsing for all employees over a single connection.

PostMaster Enterprise is the standard bearer of the IQuinox platform - a framework that provides user customizable rules to introduce process and measurability into the Internet communication channels that an organization uses. The Robot Service of PostMaster Enterprise is an extension of this rules framework into this application.

qmail is a secure, reliable, efficient, simple message transfer agent. It is designed for typical Internet-connected UNIX hosts. As of October 2001, qmail is the second most common SMTP server on the Internet, and has by far the fastest growth of any SMTP server.