What exactly happens when a user sends a 300MB attachment?

[dpsmith]

Hello.
Exchange Newbie here.

What exactly happens when a user sends a 300MB attachment?
Other than totally messing up my Exchange 2007 server and bringing the whole thing to a crawl?

Lets ignore the fact that she tried to send this attachment, lol.

The server is solo, meaning that it does everything.
There's no addition servers that do any exchange duties.
But it's NOT a domain controller.
400 email accounts in total.
Plenty of RAM ad storage space.

I already set up a 20MB limit on attachments.

Never had any problems.

But when this woman sent this attachment and my email system began to flush down the toilet with slowness I could not troubleshoot what was going on!
I checked the queues for a problem, nothing.
Performance monitor...nothing
Ran the Exchange troubleshooter and it told me it was "slow" due to network traffic.

I stopped the Exchange services and restarted.
That made things better for a few hours then it was right back to numerous phone calls from the company complaining of slowness.
I then stopped the services and then rebooted the server.
It came right back up and ran good but then 12 hours later it was back to a crawl.

I deleted the emails from her outbox again and things are back to normal but I'm waiting for it to hit again.

I only found out about the attachment issue because the user got on the phone with me and said that her email that she sent yesterday was stuck in her outbox.
It took an incredible amount of time gain access to her outbox through the Outlook 2007 client.
That's when I saw the attachment size and deleted it.

But....a few hours later it was back twice.
I've read that if the destination rejects the email it can bounce back?
Did that email actually get out of my company and get bounced?
But why would it show up in her outbox?

Clearly I have something not set up properly!

How should I have found and solved the issue of a megasized attachment like that?

 

[dpsmith]

I figured out this to prevent it from happening again:

Set-TransportConfig -MaxSendSize 15MB

But I'd still like to hear how others might have troubleshot the issue.
Like I said, if that end user didn't speak up I'd never had known.

 

[xmsre]

When you send, it goes to the transport hub and then to the mailbox or external. Set -transportconfig is the right place to set the limit.

As the message gets spooled into the transport hub database, I could see where you'd have problems with version buckets and disk. The hub database is realitivly small and unless you put it somewhere else, it's on the mirror with your system files. See

http://technet.microsoft.com/en-us/library/bb201658.aspx

 

[58sniper]

I wrote about back pressure problems involving the transport queue, and how to move it at

http://www.petri.co.il/back-pressure-moving-queue-database-in-exchange-2007.htm

Pat Richard MVP
Plan for performance, and capacity takes care of itself. Plan for capacity, and suffer poor performance.

http://www.ucblogs.net/blogs/exchange/