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Postfix Documentation
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Trouble shooting with qshape

Large numbers in the qshape output represent a large number of messages that are destined to (or alleged to come from) a particular domain. It should be possible to tell at a glance which domains dominate the queue sender or recipient counts, approximately when a burst of mail started, and when it stopped.

The problem destinations or sender domains appear near the top left corner of the output table. Remember that the active queue can accommodate up to 20000 ($ qmgr_message_active_limit) messages. To check wether this limit has been reached, use:

$ qshape -s active | head       (show sender statistics)

If the total sender count is below 20000 the active queue is not yet saturated, any high volume sender domains show near the top of the output.

The active queue is also limited to at most 20000 recipient addresses ($ qmgr_message_recipient_limit). To check for exhaustion of this limit use:

$ qshape active | head          (show recipient statistics)

Having found the high volume domains, it is often useful to search the logs for recent messages pertaining to the domains in question.

# Find deliveries to example.com
#
$ tail -10000 /var/log/maillog |
        egrep -i ': to=<.*@example\.com>,' |
        less

# Find messages from example.com
#
$ tail -10000 /var/log/maillog |
        egrep -i ': from=<.*@example\.com>,' |
        less

You may want to drill in on some specific queue ids:

# Find all messages for a specific queue id.
#
$ tail -10000 /var/log/maillog | egrep ': 2B2173FF68: '

Also look for queue manager warning messages in the log. These warnings can suggest strategies to reduce congestion.

$ egrep 'qmgr.*(panic|fatal|error|warning):' /var/log/maillog

When all else fails try the Postfix mailing list for help, but please don't forget to include the top 10 or 20 lines of qshape(1) output.

Postfix Documentation
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