How to disable IPv6 in Postfix

If you send mail to gmail server without correct PTR records, you'll get the reject message below.

"message does not meet IPv6 sending guidelines regarding PTR records 550-5.7.1"

You may update PTR record, or disable IPv6 if you don't need it.


Edit main.cf

Update the value with ipv4 in this line "inet_protocols = all"

inet_protocols = ipv4



You might get another message  "config variable inet_interfaces: host not found: [::1]"

Update the value with 127.0.0.1 in this line "inet_interfaces = 127.0.0.1, [::1]" will solve the problem.