Best way to measure sendmail queue depth?

Stephen Swaney steve.swaney at
Sat Jun 17 02:45:46 IST 2006

> -----Original Message-----
> From: mailscanner-bounces at [mailto:mailscanner-
> bounces at] On Behalf Of campbell at
> Sent: Friday, June 16, 2006 7:02 PM
> To: MailScanner discussion
> Subject: Re: Best way to measure sendmail queue depth?
> Quoting "Furnish, Trever G" <TGFurnish at>:
> > I've been checking sendmail inbound queue depth using a simple readdir
> > and dividing the number of entries by two.  This is checked every five
> > minutes by Nagios with a 10-second timeout -- because of the timeout and
> > the frequency with which I want to do the check, I can't just use, for
> > example:
> >
> >     mailq |head -1
> >
> > ...because under heavy flow conditions the mailq command takes WAY too
> > long to parse the entire set of queue files and generates too much load.
> >
> > I always realized dividing the number of files in the queue by two was
> > only a rough guess, but I didn't realize there could be so much
> > disparity between that number and the number of messages listed by
> > mailq.  With mailq reporting 6 messages in the inbound queue, the
> > directory actually contains 477 files!
> The multitude of non-paired files are probably DATA files (df) of some
> incomplete connections. You can probably delete all of these, but I would
> check
> the times on them first. This is more than likely an attempt to clog up
> your MTA.
> You could use a script with 'find' telling you which ones are older than a
> certain time period (one day should be very safe, one hour is probably
> OK), and
> delete them. Just a simple one-liner in your cron. Other than that, I'm
> sure
> there are sendmail options that would take care of this too, but they
> don't jump
> to mind right now, probably 'timeout_' options are the easiest to do.
> >
> > Mailq's result seems to match the count of files starting with a
> > lowercase "q".  I also have about the same number of files starting with
> > an uppercase "Q".  The rest of the files are df files, most of them
> > without any corresponding q file.
> The 'Qf' files, I believe, are non-deliverable files, those that can't be
> delivered even to postmaster. They are renamed qf files.
> Hope this is accurate.
> Steve Campbell
> >
> > Any idea what's going on?  Previously I expected to find files that
> > started with qf, df, xf, and tf (not Q), and to always have pairs of
> > files.  Obviously my expectation was pretty far off. :-)
> >
> > --

To find "orphaned" files from dropped or munged MTA connections (and only
for sendmail systems) probably the command you want to use first is:

	find /var/spool/ -mmin +120 -exec ls -l {} \; | more

After examining the output and verifying that the all the files listed are
more than 2 hours old, then run:

	find /var/spool/ -mmin +120 -exec /bin/rm {} \;

Be careful. Typos can wipe out your operating system :(

If you continue to see a LOT of these orphaned files, check that:

	Lock Type = 

In MailScanner .conf is set correctly for your version of sendmail (hint
search the MailScanner archives).

A good weekend to all!


Stephen Swaney
Fort Systems Ltd.
stephen.swaney at

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