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Postfix Documentation
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Introducing the qshape tool

When mail is draining slowly or the queue is unexpectedly large, run qshape(1) as the super-user (root) to help zero in on the problem. The qshape(1) program displays a tabular view of the Postfix queue contents.

  • On the horizontal axis, it displays the queue age with fine granularity for recent messages and (geometrically) less fine granularity for older messages.

  • The vertical axis displays the destination (or with the "-s" switch the sender) domain. Domains with the most messages are listed first.

For example, in the output below we see the top 10 lines of the (mostly forged) sender domain distribution for captured spam in the " hold" queue:

$ qshape -s hold | head
                         T  5 10 20 40 80 160 320 640 1280 1280+
                 TOTAL 486  0  0  1  0  0   2   4  20   40   419
             yahoo.com  14  0  0  1  0  0   0   0   1    0    12
  extremepricecuts.net  13  0  0  0  0  0   0   0   2    0    11
        ms35.hinet.net  12  0  0  0  0  0   0   0   0    1    11
      winnersdaily.net  12  0  0  0  0  0   0   0   2    0    10
           hotmail.com  11  0  0  0  0  0   0   0   0    1    10
           worldnet.fr   6  0  0  0  0  0   0   0   0    0     6
        ms41.hinet.net   6  0  0  0  0  0   0   0   0    0     6
                osn.de   5  0  0  0  0  0   1   0   0    0     4
  • The "T" column shows the total (in this case sender) count for each domain. The columns with numbers above them, show counts for messages aged fewer than that many minutes, but not younger than the age limit for the previous column. The row labeled "TOTAL" shows the total count for all domains.

  • In this example, there are 14 messages allegedly from yahoo.com, 1 between 10 and 20 minutes old, 1 between 320 and 640 minutes old and 12 older than 1280 minutes (1440 minutes in a day).

By default, qshape shows statistics for the union of both the incoming and active queues which are the most relevant queues to look at when analyzing performance.

One can request an alternate list of queues:

$ qshape deferred | less
$ qshape incoming active deferred | less

this will show the age distribution of the deferred queue or the union of the incoming active and deferred queues.

Command line options control the number of display "buckets", the age limit for the smallest bucket, display of parent domain counts and so on. The "-h" option outputs a summary of the available switches.

Postfix Documentation
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