This project provides the SPF (Sender Policy Framework) back-end for both
pypolicyd-spf (for which it was originally developed) and an future SPF
milter using pymilter. The goal is to provide a common back-end for common
features for support SPF integration with Postfix and Sendmail using both
the Postfix policy service and the Sendmail milter protocol (also available
with Postfix).

WWW: https://launchpad.net/spf-engine