I manage a site that has a number of mail forwarding addresses. They use it as a simple way to distribute information to various groups of people. Problem: Some mail servers reject the forwarded email. This happens when the forwarder receives a DKIM signed email and forwards it out. I understand SRS will correct this issue (the people are quite non-technical. Mailman would mean it would be quite possible that none of those using these Mailman will readily grasp the change). Running Postfix under Debian Wheezy installed following: The Perfect Server - Debian Wheezy (Apache2, BIND, Dovecot, ISPConfig 3).