We are running MS Exchange 2003 and MS Outlook 2000.
When sending an email with no attachment, it sends. The email is received.
When sending an email with a small attachment (such as a notepad file), it sends. The email is received.
When sending an email with a larger attachment (such as 1MB or larger), it gives the following error:
"Network problems are preventing connection to Microsoft Exchange server computer..."
The same thing happened on two different PCs on the same network/domain.