Mailing List Archive: Qmail: users

Multiple NDR's for one E-Mail

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mhutchinson at manux

Jun 11, 2008, 2:02 PM

Post #1 of 3 (470 views)
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Multiple NDR's for one E-Mail

Hello everyone,

I have an intermittent problem with out Qmail server here at work.

We're running netqmail 1.05, vpopmail, spamassassin, clamav.

Occasionally a user will report receiving multiple NDR's for one
incorrectly addressed E-Mail. This wasn't so much of an issue until one
of the incorrectly addressed E-Mails contained an attachment of around
4Mb in size, which bounced back around 8 times, causing un-necessary
load on the server side, and client side. I would hate to think what a
40Mb attachment would do - I know our server would handle this, but the
client is going to get very annoyed.

The NDR's come back with the full attachment, and they all state the
originating message is undeliverable because the recipient is invalid.

I'm afraid I do not have copies of the messages, the last time this
happened I was off sick and didn't get a chance to save the messages out
before they were deleted by other staff.

Has anyone had this problem before, or know where to look for problems
with my Qmail setup?

Cheers,

Michael Hutchinson

kyle-qmail at memoryhole

Jun 11, 2008, 3:08 PM

Post #2 of 3 (442 views)
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Re: Multiple NDR's for one E-Mail [In reply to]

On Thursday, June 12 at 09:02 AM, quoth Michael Hutchinson:
> Occasionally a user will report receiving multiple NDR's for one
> incorrectly addressed E-Mail. This wasn't so much of an issue until
> one of the incorrectly addressed E-Mails contained an attachment of
> around 4Mb in size, which bounced back around 8 times, causing
> un-necessary load on the server side, and client side. I would hate
> to think what a 40Mb attachment would do - I know our server would
> handle this, but the client is going to get very annoyed.

The first place to look is your log files. Make sure it's actually
your fault before getting too stressed out! Locate the logs of the
delivery of the eight NDRs, and then work your way back in the logs to
find where they came from. Here are some questions to try to answer...
the answers will tell you what's going on:

1. Was the NDR generated by YOUR server?
2. How many times was the NDR injected into your queue?
3. If it was injected only once, delivery failures may have caused
it to be delivered multiple times. Did delivery attempts fail?
- Why did they fail?
4. If it was injected into the queue eight times, the sender
(possibly your own qmail-send process---find out!) may have had
trouble getting it into the queue. Did the sender have trouble
queueing the NDR?
- What kind of trouble?

> I'm afraid I do not have copies of the messages, the last time this
> happened I was off sick and didn't get a chance to save the messages
> out before they were deleted by other staff.

Without that, you can do *some* log spelunking, but unless there's
something obvious in your logs to help answer the previous questions,
you're probably going to end up just chasing your tail, unfortunately.

Good luck!

~Kyle
--
It has been my experience that folks who have no vices have very few
virtues.
-- Abraham Lincoln

mhutchinson at manux

Jun 11, 2008, 3:28 PM

Post #3 of 3 (440 views)
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RE: Multiple NDR's for one E-Mail [In reply to]

Hello Kyle,

Firstly, sorry for the top posting, my outlook doesn't do quoting
properly.
Secondly, Thank-you for your intuitive response, I will begin work on
answering those questions for our server.

Thank you for your help, Kyle, no doubt by following your advice I will
be able to solve this problem.

Cheers,
Michael Hutchinson.

-----Original Message-----
From: Kyle Wheeler [mailto:kyle-qmail[at]memoryhole.net]
Sent: Thursday, 12 June 2008 10:09 a.m.
To: qmail[at]list.cr.yp.to
Subject: Re: Multiple NDR's for one E-Mail

On Thursday, June 12 at 09:02 AM, quoth Michael Hutchinson:
> Occasionally a user will report receiving multiple NDR's for one
> incorrectly addressed E-Mail. This wasn't so much of an issue until
> one of the incorrectly addressed E-Mails contained an attachment of
> around 4Mb in size, which bounced back around 8 times, causing
> un-necessary load on the server side, and client side. I would hate
> to think what a 40Mb attachment would do - I know our server would
> handle this, but the client is going to get very annoyed.

The first place to look is your log files. Make sure it's actually
your fault before getting too stressed out! Locate the logs of the
delivery of the eight NDRs, and then work your way back in the logs to
find where they came from. Here are some questions to try to answer...
the answers will tell you what's going on:

1. Was the NDR generated by YOUR server?
2. How many times was the NDR injected into your queue?
3. If it was injected only once, delivery failures may have caused
it to be delivered multiple times. Did delivery attempts fail?
- Why did they fail?
4. If it was injected into the queue eight times, the sender
(possibly your own qmail-send process---find out!) may have had
trouble getting it into the queue. Did the sender have trouble
queueing the NDR?
- What kind of trouble?

> I'm afraid I do not have copies of the messages, the last time this
> happened I was off sick and didn't get a chance to save the messages
> out before they were deleted by other staff.

Without that, you can do *some* log spelunking, but unless there's
something obvious in your logs to help answer the previous questions,
you're probably going to end up just chasing your tail, unfortunately.

Good luck!

~Kyle
--
It has been my experience that folks who have no vices have very few
virtues.
-- Abraham Lincoln

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