The magically blocked PDF

This just started about six weeks ago.

Incomming mail arrives fine.
Outgoing mail is delivered fine, unless it contains a PDF attachment, and only if that PDF attachment is 2MB+ in size.  Should this 2MB attachment be split into two 1MB attachments, and sent one at a time, both arrive fine.

There are no send or receive limits set for Exchange.

These 2MB+ PDF messages just sit in the queue.  We first noticed this after 5 days had passed.

After a reboot, they are sent out and delivered as intended.  For a period everything works fine, then some random time later (few days to a week, no definate trigger,) process starts over again.  2MB+ of other files can get sent fine, PDFs 2MB+ sit in queue.  Reboot, delivered, rinse and repeat.  No significant errors being reported with OS, Exchange, DNS, AV.

Any ideas?
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Check the size of the mail being sent from ur exchange server.
What kind of Firewall do you have?
Check this link. It looks like you firewall is interfering with the delivery.

it should not be the firewall because user is saying that it is stuck in the smtp queue (Please tell me if i understand it incorrectly). It is not even going from exchange to firewall

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olivejarAuthor Commented:

that is close, and gives me something to go on.  It's a watchguard firewall (x15 to be exact.)

That persons are being sent and resent.  In my case, some with PDFs are not being sent at all.  On the firewall, it's a lower model, so there are no proxys... it's simple port forwarding, so I am thinking that SMTP commands are not being filtered out.  In any case, I am also going to bother Watchguard with this now too.

ksharma4:  I do not think it is the firewall either, as there is no proxy/filter, and only port forwarding.  But, this would not be the first time I've encountered a Watchguard product fighting with another product/application.  If the firewall is playing with the SMTP commands, i can imagine Exchange thinking "ok, that didn't go so well. I will try to redeliver again later."

But I am not so sure it is the firewall anyway.  At one of their machines, I send three email to one of my accounts.  1) "Hello" 2) "hello" with 1MB PDF, and 3) "hello" with 2MB PDF.  #1 and #2 are delivered to me fine.  #3 sits in the Exchange queue until a reboot occurs.  Even "force connection" does nothing until rebooted.
olivejarAuthor Commented:
Made some headway, but not much.

took the firewall out of the loop.
attempted to send the PDF in question again.
Hits and sits in exchange queue.
1 hour passes and nothing.
"Force connection" and delivers as intended.

took the firewall out, so it's not the firewall.
AV? sure maybe, but 1) pdf is not a blocked extension, 2) sends fine when "force connection"
olivejarAuthor Commented:
Mcafee has a --feature-- for real-time scanning. Something about blocking large traffic over port 25, as it could be a worm.

disabled that and all is well.
PAQed with points refunded (500)

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