IMAP List Administration:
> 1) is it possible that we are observing a bug in postfix in conjunction with
> DNS-queries? Are there any such known bugs?
If Postfix replies with 4xx unknown client, Postfix got an "soft"
error FROM THE SYSTEM LIBRARY ROUTINES that the domain could not
be looked up. There was a timeout or some other error that prevented
THE SYSTEM LIBRARY ROUTINES from receiving the information theat
Postfix asked for.
If Postfix replies with 5xx unknown client, Postfix got a "hard"
error FROM THE SYSTEM LIBRARY ROUTINES that the domain could not
be looked up. THE SYSTEM LIBRARY ROUTINES received a reply from
the DNS server that the name does not exist.
Wietse
