I'm in a bit of a pickle here. We've recently switched broadband providers and for some reason, our outgoing emails get stuck in the Outgoing folder in Outlook 2010. They only get sent after restarting the application.
I have recently took off DNS and DHCP duties off the router and put them on our W2k8 server, thinking it could help.
Our current accounts are with CobWeb (hosted Exchange), but I have added an Office 365 Exchange account to my profile and that one works just fine. I have done a trace route to CobWeb's Exchange server and I don't see anything strange. This only happens when we are connected over Ethernet, if I connect over wireless directly to the BT Internet gateway, it works just fine.
The connection goes like this:
BT Gateway -> Cisco router (for backup line) -> Switch -> Server and PC's
I have checked every point of failure I can think of, enabled logging in Outlook but couldn't see anything wrong.
What do you think it is?
If you need more details please let me know!
UPDATE: I have ran more tests and the Office 365 account fails too. I am able to send about 3 or 4 emails after opening Outlook, then they get stuck again in the Outbox until the application is restarted.