Features are implemented using the flexible plugin framework. Below are the current official plugins.
Protocol plugins provide protocol support for different MTAs.
Support for the Postfix SMTPD delegation protocol
Support for Bizanga using the HTTP protocol
Modules provide various features and enhancements to Policyd.
Access control lists. Matching policies can have verdicts of HOLD, REJECT, DISCARD, FILTER, REDIRECT and contain optional verdict data.
Support for Amavisd-new.
Support for various HELO/EHLO checks.
Support for various SPF checks.
Greylisting support.
Rolling window quotas.
Usage based accounting (Supported in: r343, v2.1.x).