1 Introduction to mailfromd

Mailfromd is a general-purpose mail filtering daemon and a suite of accompanying utilities for Sendmail², MeTA1³, Postfix⁴ or any other MTA that supports Milter (or Pmilter) protocol. It is able to filter both incoming and outgoing messages using a filter program, written in mail filtering language (MFL). The daemon interfaces with the MTA using Milter protocol.

The name mailfromd can be thought of as an abbreviation for ‘Mail Filtering and Runtime Modification’ Daemon, with an ‘o’ for itself. Historically, it stemmed 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 language translator and run-time evaluator providing a set of built-in and library functions for filtering electronic mail.

The first part of this manual is an overview, describing the features mailfromd offers in general.

The second part is a tutorial, which provides an introduction for those who have not used mailfromd previously. It moves from topic to topic in a logical, progressive order, building on information already explained. It offers only the principal information needed to master basic practical usage of mailfromd, while omitting many subtleties.

The other parts are meant to be used as a reference for those who know mailfromd well enough, but need to look up some notions from time to time. Each chapter presents everything that needs to be said about a specific topic.

The manual assumes that the reader has a good knowledge of the SMTP protocol and the mail transport system he uses (Sendmail , Postfix or MeTA1).