Getting lots of Undeliverable: Returned mail: see transcript for details

[Jacobs, Eric (ThomasTech)]

> -----Original Message-----
> From: mailscanner-bounces at lists.mailscanner.info 
> [mailto:mailscanner-bounces at lists.mailscanner.info] On Behalf 
> Of Jon Radel
> Sent: Monday, April 17, 2006 9:53 PM
> To: MailScanner discussion
> Subject: Re: Getting lots of Undeliverable: Returned mail: 
> see transcript for details
> 
> 
> 
> Scott Silva wrote:
> > Billy A. Pumphrey spake the following on 4/15/2006 7:53 PM:
> > 
> >>Since I upgraded to near the latest MailScanner, I am 
> getting a lot of
> >>these.
> >>
> >>Your message did not reach some or all of the intended recipients.
> >>
> >>      Subject:	Returned mail: see transcript for details
> >>      Sent:	4/15/2006 9:32 PM
> >>
> >>The following recipient(s) could not be reached:
> >>
> >>      jelki at selena.net.ua on 4/15/2006 9:32 PM
> >>            The message could not be delivered because the 
> recipient's
> >>destination email system is unknown or invalid. Please 
> check the address
> >>and try again, or contact your system administrator to verify
> >>connectivity to the email system of the recipient.
> >>            < WoodenMS2.woodmaclaw.local #5.1.2>	
> >>
> >>Any idea why this is happening?  I figure that is is DNS related or
> >>something.
> >>
> >>Thank you
> > 
> > I tried a smtp verify on that user at that domain;
> > User does not exist....
> > 
> > 
> 
> It would possibly make more sense if Mr. Pumphrey read down a bit and 
> looked at the rest of the mail (aren't the original e-mails 
> attached?). 
>   I see a lot of those in the postmaster, address of last 
> resort, e-mail 
> from the following:
> 
> 1) Spam from non-existent address is sent to non-existent user on my 
> sendmail server.
> 
> 2) Bounce to non-existent from address is prepared.
> 
> 3) Bounce bounces and notice of this second bounce goes to postmaster.
> 
> I suspect that as part of the upgrade either the option to quietly 
> discard these was turned off in the MTA or MailScanner is no longer 
> "discarding" them.  I suspect the root cause was there before.
> 
> --Jon Radel
> jon at radel.com
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>

I was having the same problem for awhile. What was triggering it was spam
that was coming in as a "gif" attachment with an extremely long filename.
While spamassassin was recognizing it as spam, it was also being flagged by
MailScanner's filename checking. I do have MailScanner to notify upon
blocking attachments because many clients will send banned attachments, so
it was sending notifications about these blocked messages, which, of course,
were bouncing. I got around this by putting gif attachments in the
MailScanner.conf's "Allow filenames" entry, thus bypassing the
filename.rules.conf check for these e-mails.

Eric Jacobs