Version 10 (modified by kmkaplan, 11 years ago)


Copyright 2007 by Kim Minh Kaplan

Greyfix is the greylisting policy daemon for Postfix written by Kim Minh Kaplan. Greylisting is an anti spam technique described by Evan Harris. Postfix is a popular mail transport agent developped by Wietse Zweitze Venema. Greyfix uses Postfix policy mechanism to enable greylisting with Postfix.

It is recommended that you upgrade to the latest version.

Latest version (PGP signature)

  • Do not block emails if there is an error. Previous versions would die. This would cause Postfix's smtpd to reply with an error code 500 and the email would bounce. Now Greyfix will log a warning and let the email continue.
  • BUGFIX: expire correctly IDLE triplets.


  • Low and tunable resource usage and high efficiency. The program is written in C and uses Berkeley DB to track mailers. By itself it allocates memory only for a single request and the Berkeley DB library can be configured to use very few RAM.
  • Integrates with Postfix's master daemon. Postfix will shutdown greyfix when it is not used completely freeing its runtime resources.
  • No administrative burden. Everything happens "automagically".
  • No need for a database server. Uses Berkeley DB which is already installed with most free Unix distributions.


  • Postfix 2.1 or later. Greyfix is designed exclusively for it. It will not work with other mailers.
  • Berkeley DB 4.0 or later. Chances are you already have it.