Deliveries to mailboxes on my Domain failing randomly

Hi there.

I have been getting odd errors over the past couple of weeks where assorted people outside of my organisation have been having mail bounced back when trying to send to some mailboxes on my domain. The DSN's are telling the sender that the Exchange mailbox/user has exceeded their storage allocation.

This is strange in that I have only set a 'soft limit' on the mailboxes in my domain. The user receives a notification but the mailbox is still allowed to send and receive mail at all times. Also, upon checking the mailstore sizes for the accounts concerned I found that they were not actually at the limit anyway!

I have included the text from a DSN below:

-----Original Message-----
Sent: Monday, October 18, 2004 12:59 PM
Subject: failure notice

This is the mail delivery agent at
I was not able to deliver your message to the following addresses.

<>: failed after I sent the message.
Remote host said: 552 Requested mail action aborted: exceeded storage

--- Below this line is a copy of the message.

Return-Path: <>
X-VirusChecked: Checked
X-StarScan-Version: 5.2.10;,-,-
X-Originating-IP: []
Received: (qmail 25991 invoked from network); 18 Oct 2004 11:58:46 -0000
Received: from mail. (HELO Internet.) (
  by with SMTP; 18 Oct 2004 11:58:46 -0000
Received: from SMTP agent by mail gateway
 Mon, 18 Oct 2004 12:55:58 -0800
Received: by INTERNET with Internet Mail Service (5.5.2653.19)
      id <KPC5L7G5>; Mon, 18 Oct 2004 13:08:32 +0100
Message-ID: <E1A350AB4BA8D5118EDF009027E4032A01DE8713@INTERNET>
From: Richard Denyer <>
To: < >
Subject: RE:
Date: Mon, 18 Oct 2004 13:08:28 +0100
MIME-Version: 1.0
X-Mailer: Internet Mail Service (5.5.2653.19)
Content-Type: multipart/alternative;

This message is in MIME format. Since your mail reader does not understand
this format, some or all of this message may not be legible.

Content-Type: text/plain;

Thanks for any help you can offer.
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Hi mellingham,
Well, this is only a cursory analysis but do you have any policies which are limiting the sizes of *attachments*? This could potentially cause the same problem even if quotas are not being reached.

Well, it could also be your firewall. I don't know what kind of firewall solution you have but it may be blocking certain emails which are unterminated, you may want to look into this as well.
mellinghamAuthor Commented:
Thanks for the quick response!

I have implemented max incoming and outgoing message sizes which are limited to 10MB. I would have thought that this would have generated a 'chunk too large' error or something like that but I have checked with the users to see if they were receiving any large attachments from these senders and they seem to think not.

Do you think 10MB is a fair limit or should I up it to see if the problem stops?

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mellinghamAuthor Commented:
Had looked at the firewall logs to be on the safe side but the message our firewall gives out is quite different and specific to stripping attachments. Is very odd indeed!
Well 10MB is fine. Are you enabling an smtp-proxy via the firewall?
mellinghamAuthor Commented:
Hi again...sorry I've been on holiday!

I do have an SMTP proxy via my WatchGuard Firewall. What were you thinking?
mellinghamAuthor Commented:
Hi again.

I think I have nailed it. I checked the Domains that were unable to send to me and it appears that these mail servers do not have a reverse DNS lookup set up. This has been occuring when my mail server has been unavailable and our store-and-forward provider has been taking all the SMTP connections. It turns out that they do not accept connections from servers with no reverse lookup.

Thanks for looking...applying for a closure.
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