Problems sending mail with Postfix after update - Centos 4.7

Installing, Configuring, Troubleshooting server daemons such as Web and Mail
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harrya
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Joined: 2009/05/28 14:14:20

Problems sending mail with Postfix after update - Centos 4.7

Post by harrya » 2009/05/28 15:47:37

Over the weekend a number of packages were automatically updated on our Centos 4.7 installation.
Subsequently we have found that we have not been able to send emails (using postfix) other than very short ones (i.e. subject and message body are both 'test'). The postfix configuration has not changed since March so this probably isn't the source of the problem.
We get this error for failed emails in the mailog:

May 28 16:06:23 kirkstall postfix/smtp[8213]: 57FFEC74403: to=, relay=x.x.x.x[x.x.x.x], delay=24458, status=deferred (lost connection with x.x.x.x[x.x.x.x] while sending end of data -- message may be sent more than once)

I tried googling the issue and some pages pointed me toward disabling PMTU discovery - http://www.postfix.org/faq.html#timeouts. I tried this by setting net.ipv4.ip_no_pmtu_disc to 1 and then reloading the config using sysctl -p but to no avail.

The packages that were updated were:

cups-1.1.22-0.rc1.9.27.el4_7.5
acpid-1.0.3-2.el4_7.1
NetworkManager-gnome-0.3.1-5.el4
gpdf-2.8.2-7.7.2.el4_7.4
evolution28-pango-1.14.9-11.el4_7
tzdata-2009f-1.el4
pidgin-2.5.5-1.el4
kdegraphics-3.3.1-13.el4
evolution-2.0.2-41.el4_7.2
ghostscript-7.07-33.2.el4_7.8
NetworkManager-0.3.1-5.el4
libpurple-2.5.5-1.el4
cups-libs-1.1.22-0.rc1.9.27.el4_7.5
evolution-data-server-1.0.2-14.el4_7.1
libsoup-2.2.1-4.el4.1
pango-1.6.0-14.4_7
lftp-3.7.14-1.el4.rf

We are running kernel 2.6.9-78.0.22.ELsmp.

Any assistance would be appreciated.

pschaff
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Problems sending mail with Postfix after update - Centos 4.7

Post by pschaff » 2009/05/28 20:48:55

Looks like a network-related issue and NetworkManager was updated. Are you using NetworkManager or the networking service?

harrya
Posts: 2
Joined: 2009/05/28 14:14:20

Re: Problems sending mail with Postfix after update - Centos 4.7

Post by harrya » 2009/06/02 08:24:36

Thanks for your reply Phil.
We managed to get to the bottom of this issue. It turned out that our modem/router was only allowing us upload speeds of around 1.5KB/s. This meant that that all but the smallest of messages were being timed out by the server we were relaying through.
We changed the modem/router and our mail queue emptied almost immediately after it was flushed.

pschaff
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Posts: 18276
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Location: Tidewater, Virginia, North America
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Re: Problems sending mail with Postfix after update - Centos 4.7

Post by pschaff » 2009/06/02 11:42:08

Thanks for reporting back, and forgot to say - welcome to the CentOS fora.

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