[Dovecot] limit number of simultaneous lmtp deliveries ?
We have quite a few frontend mail gateways that deliver incoming email trough our dovecot director (lmtp proxy) to the backend lmtp servers, and are seeing this logged on the frontend mail gateways:
Sep 5 10:51:56 mailgw1 postfix/lmtp[23443]: 0E2F41C01A: to=<me@example.com>, relay=loadbalancers.example.com[192.168.42.15]:24, delay=61, delays=0.02/0.3/31/30, dsn=4.4.0, status=deferred (host loadbalancers.example.com[192.168.42.15] said: 451 4.4.0 Remote server not answering (DATA output timeout) (in reply to end of DATA command))It's a bit unclear to me if this leads to duplicate deliveries, or just delayed deliveries, but -- is there any way to limit the number of simultanous deliveries on either the dovecot director or the backend lmtp-servers ?
Will "process_limit=10" work for "service lmtp"?
-jf
On Mon, 2011-09-05 at 11:05 +0200, Jan-Frode Myklebust wrote:
We have quite a few frontend mail gateways that deliver incoming email trough our dovecot director (lmtp proxy) to the backend lmtp servers, and are seeing this logged on the frontend mail gateways:
Sep 5 10:51:56 mailgw1 postfix/lmtp[23443]: 0E2F41C01A: to=<me@example.com>, relay=loadbalancers.example.com[192.168.42.15]:24, delay=61, delays=0.02/0.3/31/30, dsn=4.4.0, status=deferred (host loadbalancers.example.com[192.168.42.15] said: 451 4.4.0 Remote server not answering (DATA output timeout) (in reply to end of DATA command))
It's a bit unclear to me if this leads to duplicate deliveries, or just delayed deliveries,
Possibly randomly either one. I'll need to start looking into these LMTP proxy bugs some day.. Although for 2.0.14 I improved the error messages a little. Is this from 2.0.14 or earlier?
but -- is there any way to limit the number of simultanous deliveries on either the dovecot director or the backend lmtp-servers ?
Will "process_limit=10" work for "service lmtp"?
It'll work for both directory and backend, yes. Although each lmtp process can also handle multiple clients. So you might also want to set client_limit=1. Actually that could be a good idea to try in any case to see if it helps with these problems.
On Mon, Sep 05, 2011 at 07:50:20PM +0300, Timo Sirainen wrote:
Possibly randomly either one. I'll need to start looking into these LMTP proxy bugs some day.. Although for 2.0.14 I improved the error messages a little. Is this from 2.0.14 or earlier?
It's with v2.0.14 on both director and backend lmtp servers.
Will "process_limit=10" work for "service lmtp"?
It'll work for both directory and backend, yes. Although each lmtp process can also handle multiple clients. So you might also want to set client_limit=1. Actually that could be a good idea to try in any case to see if it helps with these problems.
I now tested with:
process_limit=10
client_limit=1on both directors and backend lmtp servers, but I'm still getting these same failures. Since you're hinting about "lmtp proxy bugs", I think I'll try if it works better to skip the director/proxy and just have postfix deliver directly to backend lmtp-servers directly.
-jf
On 5.9.2011, at 12.05, Jan-Frode Myklebust wrote:
Sep 5 10:51:56 mailgw1 postfix/lmtp[23443]: 0E2F41C01A: to=<me@example.com>, relay=loadbalancers.example.com[192.168.42.15]:24, delay=61, delays=0.02/0.3/31/30, dsn=4.4.0, status=deferred (host loadbalancers.example.com[192.168.42.15] said: 451 4.4.0 Remote server not answering (DATA output timeout) (in reply to end of DATA command))
Well, I added even more debugging output for this message: http://hg.dovecot.org/dovecot-2.0/raw-rev/8de8752b2e94
Would be interesting to know what it logs with that.
On Thu, Sep 08, 2011 at 01:42:16PM +0300, Timo Sirainen wrote:
Well, I added even more debugging output for this message: http://hg.dovecot.org/dovecot-2.0/raw-rev/8de8752b2e94
Would be interesting to know what it logs with that.
Postfix logs:
Sep 8 13:14:28 asav7 postfix/lmtp[22024]: 5ADD454030: host loadbalancers.example.com[192.168.42.15] said: 451 4.4.0 Remote server not answering (DATA output stalled for 30 secs, 36742B sent, 0B buffered) (in reply to end of DATA command)
Sep 8 13:17:51 asav7 postfix/lmtp[22759]: 1981954011: host loadbalancers.example.com[192.168.42.17] said: 451 4.4.0 Remote server not answering (DATA output stalled for 30 secs, 38629B sent, 0B buffered) (in reply to end of DATA command)-jf
participants (2)
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Jan-Frode Myklebust
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Timo Sirainen