anzelmooo .:
> Hello,
>
> We have two servers with identical configuration running Postfix 2.6.6 on
> Redhat 6.x.
Postfix support for version 2.6 was terminated 6 or more years ago.
The code that you are running is RedHat's blend of Postfix releases.
> One of the servers recently upgraded from Redhat 6.4 to Redhat 6.10. No
> major changes are reported. Postfix configuration was unchanged.
If it's the same Postfix 2.6.6 and the same configuration, then
logically, the difference is not caused by Postfix.
If you want to debug this, you can log the SMTP session (debug_peer_list
= example.com) and see if the remote server delays its QUIT response.
That could explain the 5s delay.
Such delays should not be a problem with the default setting
"smtp_skip_quit_response = yes", but maybe RedHat has changed that.
Wietse
