I was getting PTR errors on ipv6 from google mail. the rDNS for Ip4 works, but my registrar is not able to add the ipv6 ptr record for my mail server. I tried to disable ipv6 on Postfix by doing this: postfix master.cf imap -o inet_protocols = ipv4 did not work. after I force in the main.cf file inet_protocol = ipv4 it seem to work when sending to mail addresses outside the server, but when I send to mails that is on the same server I get the following error: postfix/smtpd[2962994]: fatal: cannot handle socket type AF_INET6 with "inet_protocols = ipv4" Any suggestion
Disable IPv6 completely on that host. My understanding is Postfix et al automatically use all interfaces they find, so if there are no IPv6 connections they are not used. That is very strange. Are you sure? Where did you get that IPv6 number? Your hoster should be able to set PTR for IPv6.
Read instructions for your OS and OS version, there probably is a wiki or some other form of documentation.
The error occurs because Postfix is trying to use IPv6 for local mail delivery, despite being set to IPv4. To fix this, ensure inet_protocols = ipv4 is consistently set in both main.cf and master.cf. Additionally, set inet_interfaces = all or inet_interfaces = 127.0.0.1 in main.cf to bind Postfix to IPv4 only. Then, restart Postfix and test again.
