This is a known issue, but I’ve yet to see the answer to resolve it. I’ve checked the logs, but don’t see any information on this. Let me explain more to help:
1. I have a local Exchange Server (2010 with Rollup 2 applied) on a 2008 R2 server.
2. I also have a work POP account that is attached to my Outlook 2007 SP-2 PC.
3. If I only setup the POP account in my Outlook, I can send out attachments of any size without a problem.
4. If I add my local Exchange account, I can only send POP messages without attachments. Any attachments of any size will sit in my outbox in Outlook and go nowhere.
5. I have tried to add transport rules and sending rules, but nothing helps.
I have seen this issue posted many places, but as far as I can tell, nobody has the answer as it seems to be a glitch with 2010 and maybe R2 ?