Mailfromd is a general-purpose mail filtering daemon for Sendmail, Postfix and MeTA1. It is able to filter both incoming and outgoing messages using criteria of arbitrary complexity, supplied by the administrator in the form of a script file. The daemon interfaces with the MTA using Milter or PMilter protocols.

The program name -- mailfromd -- stems from the fact that the original implementation was a simple filter implementing the sender address verification technique. Since then the program has changed dramatically, and now it is actually a specialized system providing a set of interfacing functions, along with a language translator and runtime evaluator for executing user-defined filter programs.

Here is a short list of the basic features mailfromd provides:

Mailfromd is often employed as a mail filter.