Of Qmail, Zombies and qmail-remote timeout issues.

Occasionally even in a well maintained system, qmail has issues.

One semi-common issue I get to see, is when a server we send mail to doesn’t timeout. This ties up an outgoing mail slot. Over a period of time, this can lead to issues where the whole outgoing or incoming queue is sitting doing nothing, as every connection is tied up by ‘tarpitted’ connections.

Ideally Qmail should be able to cope with these.  There are settings in qmail to control how long a connection takes, and how long it should wait for.  These settings are covered in the following files (usually set in /var/qmail/control)

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