On 2/25/2014 2:57 AM, Roberto Giordani wrote: > During one day the server deliveries about 40.000 emails, but during > working hours I receive repeated random periods where the Postfix > smtp client doesn't open any socket to destination main SMTPD server > and the maillog file write > > dsn=4.4.2, status=deferred (conversation with > smtp.xxx.it[xxx.xx.xxx.xxx] timed out while sending MAIL FROM) > > This behavior continues for about 5 minutes and on the next queue > manager run, all emails will be accepted and delivered. > > At first time I though the problem was on the destination SMTP > server, but running tcpdump during "deferred" the server didn't open > any socket. > > Any idea to understand and fix this behavior?
Likely this started with a timeout while sending MAIL FROM, then postfix throttled the destination due to the failure. See the tips on high-volume destinations in http://www.postfix.org/QSHAPE_README.html#backlog http://www.postfix.org/TUNING_README.html -- Noel Jones
