OK. I did some tries and it seems that I cannot go above 40 Mb for message_size_limit to avoid the issue.
As you wrote, here below is a set of log lines during the issue. The emails staying in the growing active queue are the bounce messages (we intercept them to send a copy to postmaster): [root@iccpfxor04 postfix]# grep 6B34360BAA /var/log/maillog 2013-04-24T12:32:01.439701+00:00 iccpfxor04 postfix/cleanup[24423]: 6B34360BAA: message-id=<20130424123201.6b34360...@iccpfxor04.svc.unicc.org> 2013-04-24T12:32:01.442962+00:00 iccpfxor04 postfix/qmgr[24391]: 6B34360BAA: from=<double-bou...@iccpfxor04.svc.unicc.org>, size=8389, nrcpt=1 (queue active) 2013-04-24T12:32:01.442970+00:00 iccpfxor04 postfix/bounce[26517]: D4B8460078: postmaster non-delivery notification: 6B34360BAA 2013-04-24T12:36:09.981198+00:00 iccpfxor04 postfix/qmgr[27126]: 6B34360BAA: from=<double-bou...@iccpfxor04.svc.unicc.org>, size=8389, nrcpt=1 (queue active) 2013-04-24T12:40:44.391001+00:00 iccpfxor04 postfix/qmgr[27707]: 6B34360BAA: from=<double-bou...@iccpfxor04.svc.unicc.org>, size=8389, nrcpt=1 (queue active) As you can see in the logs above, it seems to be blocked in the qmgr process, sending the same "from=<double-bounce....." to the rsyslog. As soon as we rolled back to a message_size_limit of 20Mb, we've seen in the logs the message has been sent out: 2013-04-24T12:41:14.125840+00:00 iccpfxor04 postfix/local[27791]: 6B34360BAA: to=<bouncepar...@iccpfxor04.svc.unicc.org>, orig_to=<bounceparser>, relay=local, delay=553, delays=523/30/0/0.01, dsn=2.0.0, status=sent (delivered to command: /bin/bash /usr/local/bin/captureNDR) 2013-04-24T12:41:14.125943+00:00 iccpfxor04 postfix/qmgr[27707]: 6B34360BAA: removed Reindl Harald <h.rei...@thelounge.net> a écrit : > > > Am 24.04.2013 14:58, schrieb Nicolas HAHN: >> Does somebody knows what is happening? > > no because you missed to send any log-information > maybe to less memory to proceed messages with 150 MB > > ---------------------------------------------------------------- This message was sent using IMP, the Internet Messaging Program.