ACL Policy Daemon communicates with the Postfix MTA using the Policy Delegation Protocol, implementing an ACL (Access Control List) system. Key features: greylisting with flexible storage using memory for fast responses or disk for high persistence, SPF validation, control of messages by day/time, variable message size limits per domain or email, multiple RBL checking, and various ACLs available to use and combine. The configuration is simple and intuitive. License: GNU General Public License (GPL) Changes:
New ACLs: protocol_name and log. Improved debug messages. In an access statement, the action is now optional; if there is no action specified, the default action is used. The requirement has been reduced for the size ACL from smtpd_end_of_data_restrictions to smtpd_sender_restrictions. There is better handling of configuration errors.