postfix: > Mail from our system wasn't accepted oftentimes by Google either. > I discovered the following solution: Our mail server has got two IPv6 > addresses in the open Internet, one is specific, the other one > automatically created. The first one was in the DNS, the second one not. > I noticed that many times messages where sent using the automatically > generated IPv6 address, which were the mails Google rejected. Since I > introduced the automatically generated IPv6 address into the DNS, Google > accepts all mail from our server.
Solutions other than turning off IPv6 autoconfiguration on servers: - Specify all Postfix IP addresses in main.cf:inet_interfaces. /etc/postfix/main.cf: inet_interfaces = 1.2.3.4 127.0.0.1 1:2:3:4:5:6:7:8 ::1 - Specify the Postfix IPv6 address in master.cf: /etc/postfix/master.cf: relay ... smtp -o smtp_bind_address6=1:2:3:4:5:6:7:8 smtp ... smtp -o smtp_bind_address6=1:2:3:4:5:6:7:8 Wietse