That's a permission error. Somewhere in your directory hierarchy things
are off. See Postfix' set-permissions command.
But surely if Dovecot is staring as root then directory permissions are relevant, especially if I'm then asking the config to chmod the file anway ?
To me, it seems dovecot is not behaving correctly, because if it is not using root to access the directory then it is not going to be able to chmod the socket later is it ?
You should probably check few things:
1. check dmesg or /var/log/audit/audit.log for any possible security framework problems
2. check namei -vl /var/spool/postfix-authrelay/private/dovecot-auth for anything strange
3. there is some reason the socket is not bound into, dovecot creates these sockets as root.
Aki
Thanks. It ended up being an AppArmor issue. That's now fixed the socket gets created.
However, the first part of my problem described earlier still exists, namely:
2018-10-11T15:58:41.230340+01:00 X postfix-authrelay/smtpd[21297]: warning: X.example.com[X]: SASL PLAIN authentication failed:
I was hoping going via the socket instead of TCP might fix it, but apparently not. ;-(