kyle-qmail at memoryhole
Apr 30, 2008, 7:26 AM
Post #4 of 4
(119 views)
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Re: random duplicate mails received by local users
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On Wednesday, April 30 at 12:31 AM, quoth Krish:
>>> Few on my users get random duplicate messages
>> There are several ways that this can happen, all depending on your
>> setup. Generally, it's because qmail would rather send duplicates
>> than risk email disappearing, so if your delivery appeared to fail
>> (but in reality did not fail), qmail will try again until it
>> appears to have succeeded.
>
> Why would it fail ? Any common resaon ?Where must I
> check to see this..please elaborate
Why can mail delivery fail? LOTS of reasons, depending on the delivery
method. If you're delivering remotely, the failure could be because
the connection died, or because the other server suddenly crashed, or
because the other server's software was restarted, or because you
manually killed qmail-remote, or because you exceeded a timeout in
transmission... there are lots. If you're delivering locally, it can
fail because the disk is full, or because the disk is failing (and
generated an error when you tried to write things), or because some
other hardware is failing, or because you're passing it to an
application that's crashing... there are equally many reasons why
delivery could fail locally.
>>> this is reflected in outlook and webmail client as well.
>>
>> You haven't provided enough information for anyone to help you.
>> You've asked a question equivalent to "my Ford car makes a
>> squeaking noise, how do I fix it?" when we don't even know where
>> the noise is from or how often it happens or whether you recently
>> added a large mouse colony to your car.
>
> I am sorry about this but I really don't know where to
> search to provide more information. Few of my users
> receive duplicate messages when I checked the
> qmail-send logs it shows delivery made only once;
> success:0+0+1/
> I wish I could provide you with more info.
That's more information right there! In your original email, you
hadn't even given any information that would suggest what KIND of
deliveries are getting duplicate messages! Are these remote users? Are
these local users? If only one kind of user is getting duplicate
messages, that helps you track down what is going wrong. That's
*basic* stuff that you hadn't provided; like not telling your mechanic
something as basic as "the squeaking comes from the back of the car".
Describing the problem precisely is one of the most important parts of
asking for help. You also haven't told us what all patches you've
installed --- they may have important effects on basic qmail behavior
that would help figure out what's going on. You said you think pop3
might be broken, but didn't give a reason for your suspicion. You told
us that the logs show delivery success, but you didn't even go so far
as to reveal that there appears to be only ONE delivery attempt for
the duplicated messages.
If you had read the link I sent you, it would have told you what sort
of information would be useful and where to find it.
Now, you say that there's only one delivery for these duplicated
messages. The status string indicates a local delivery (but I'm just
guessing that all the duplicated messages are local - you haven't
said, so I don't know, I'm just going with the tiny bit of information
you've provided). When qmail prints out a status string like that,
it's telling you what it did with the message. "did_1+2+3" means it
delivered the message to one on-disk mailbox, forwarded it to two
other addresses, AND handed the message to three other programs. Since
your delivery says "did_0+0+1", that means that qmail handed the
message to another program. What program is that? Perhaps THAT program
is responsible for the duplication?
You would find this information either in the relevant .qmail file, or
if this is a default delivery, it would be one of the arguments that
you pass to qmail-start.
When you're debugging a delivery problem like this, what you do is try
and outline the path that the message is taking. Where does it start,
where does it finish? The idea is to find out where the duplication is
happening. Does it get injected into the queue twice? (if it does,
then each copy of the message would only be delivered once, but the
recipient would wind up with both copies). Does it get delivered
twice? (You've said that it doesn't.) What programs touch the email on
it's way into the queue and out of the queue? This is basic
information that will help you figure out how messages are being
duplicated.
~Kyle
--
We must not confuse dissent with disloyalty. When the loyal opposition
dies, I think the soul of America dies with it.
-- Edward R. Murrow
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