[Mimedefang] lost input channel.

Jonas Eckerman jonas_lists at frukt.org
Thu Sep 21 09:02:07 EDT 2006

J.P van Oyen wrote:

> Sep 17 20:46:00 www sm-mta[28696]: k8IKiuOO018686: lost input channel from
> ppp-104-23.telesat.com.co [] to MTA after mail

I see that pretty often myself. It means that the other system disconnected without telling your server about it.

It's nothing to worry about unless it results ham beeing lost or delayed.

> The domain and IP varies to quite some servers.

Seeing a lot of systems with the same strange behaviour is typical of zombie spam runs and virus outbreaks. Especially when it looks like dynamic or dialup addresses (as the one above).

> Can this have anything todo with filters through mimedefang ?

Possibly, in a way. Some viruses and spam software seem to disconnect without sending a quit if you do a REJECT or TEMPFAIL in MIMEDefang.

> Any other ideas ?

Some viruses and spam software seem to just dump a whole SMTP monologue the moment they connect and then disconnect without waiting for the receiver to actually receive and answer. If sendmail checks to see if the connection is still valid when it wants to read from a socket, it might loose the input channel before receiving everything the client sent. In that case, anything that delays sendmail reading the input would increase the likelyhood of this happening. I have not idea whatsoever if this is how sendmail works though.

Jonas Eckerman, FSDB & Fruktträdet

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