I'm looking for a sollution to the following issue: I've setup an Exchange 2007 mailserver as part of a small business 2008 server (it's a one server setup). The mailserver is generally working as it should for some months. But from the start users have experienced that they can't send out mails that are generally above 5 mb in size. In the Exchange configuration I've set the send and recieve size for emails to 35 mb, so that should not be the problem.
When a user sends a mail that is above the 5 mb threshold it ends up in the mail queue till that reaches it's time out (set at 2 hours at the moment). The error the queued messages shows is: 421 4.4.2. Connection dropped. I'm asuming this means the error isn't so much in the mailserver itself (the return error isn't about the size of the message at all) but in something else.
The Exchange server is connected to the internet through a Cisco firewall/router.
I'm looking for tips on how to troubleshoot this issue.
Thanks in advance for the help!