Date: Wed, 20 Sep 2006 17:19:05 +0200
From: "J.P van Oyen" <[EMAIL PROTECTED]>
Subject: [Mimedefang] lost input channel.
In my sendmail logs I see so now an than entries like:
Sep 17 20:46:00 www sm-mta[28696]: k8IKiuOO018686: lost input channel from
ppp-104-23.telesat.com.co [200.71.104.23] to MTA after mail
HI.
There are several possibles reasons for that.
One of them is a layer 3 network problem - MTU related.
One host is using PPPoE or similar connection that has an MTU of 1492.
As you can see by the name,
ppp-104-23.telesat.com.co
It might be the case.
The other host (your server) has MTU of 1500.
This can cause problems because PMTU doesn't work over some routers
firewall that block ICMP .
Here is a nice article about this:
Path MTU Discovery:
http://www.sendmail.org/tips/pathmtu.html
If this is the case (or might be the case), possible
solutions/workarounds are:
* ignore if it is rare and neglect able.
* Set your host MTU to 1492 instead of the default 1500.
* Disable PMTU on your server.
* Investigate further, for example check if you can see anything common
to the hosts that cause this.
Yizhar Hurwitz
http://yizhar.mvps.org
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