mqueue.in just gets bigger - no delivery?

[Logan Shaw]

On Wed, 30 Aug 2006, Brett Charbeneau wrote:
> 	Alex Broens's suggestion on the redundant rulesets was right on the
> money, but my Inbound queue continues to grow.
> 	I let MS run for a good 20 minutes and even mail sent to myself just got
> stuck in the queue and was not delivered. Meanwhile the queue continued to
> grow:
>
> Aug 30 11:51:26 franklin MailScanner[3228]: New Batch: Found 46 messages waiting
> Aug 30 11:53:06 franklin MailScanner[3228]: New Batch: Found 47 messages waiting
> Aug 30 11:55:39 franklin MailScanner[7997]: New Batch: Found 51 messages waiting
> Aug 30 11:57:10 franklin MailScanner[8046]: New Batch: Found 53 messages waiting
> Aug 30 11:57:31 franklin MailScanner[8031]: New Batch: Found 54 messages waiting
> Aug 30 12:00:45 franklin MailScanner[8383]: New Batch: Found 61 messages waiting
> Aug 30 12:01:51 franklin MailScanner[8449]: New Batch: Found 65 messages waiting
> Aug 30 12:02:51 franklin MailScanner[8449]: New Batch: Found 63 messages waiting
> Aug 30 12:05:46 franklin MailScanner[9034]: New Batch: Found 67 messages waiting
> Aug 30 12:05:59 franklin MailScanner[9139]: New Batch: Found 68 messages waiting
> Aug 30 12:10:20 franklin MailScanner[9175]: New Batch: Found 81 messages waiting
> Aug 30 12:13:35 franklin MailScanner[10652]: New Batch: Found 106 messages waiting

At this point, I think it would be worthwhile to know why the
queue is growing, or at least what component of the system is
causing it to grow.

If you are getting in 100 messages every 5 minutes and the
system can only scan 95, then you've got mail flowing properly,
but your queue size is going to grow because there is a backlog.
That's one possible explanation.

However, there are other reasons your queue might be growing.
You might be getting only a few messages, and maybe MailScanner
is appearing to process them but isn't actually removing them
from the queue.

Or maybe you have a configuration problem and MailScanner is
scanning them and putting them back into the same queue it
took them out of.  (Unlikely, but I think it's possible.)

So, to me the next step is to kill the incoming sendmail.
That will prevent *it* from putting more messages in the queue.
Then, barring anything truly weird, there is no other software
other than MailScanner that would know to put messages into
that queue.  So if the incoming sendmail is off and the number
of messages in the queue grows, you know MailScanner is adding
them.  On the other hand, if incoming sendmail is killed and
the number of messages in the queue then starts shrinking,
you know it's a backlog thing.

There are probably other diagnostics steps to analyze the
nature of messages in the queue and where the new ones are
coming from, so the above is just a starting point.

   - Logan