I'm seeing a similar problem, but no one is sending 200 MB files.
A new mailbox can send emails but can not receive emails, except locally from other users on the network. I am more knowledge with Exchange 5.5, but can move through 2000 a-okay. Checking the mailbox queues and the badmail, I do not see the messages waiting to be routed (System Manager>Administrative Groups>First Administrative Group>Servers>THEBRAIN (our server)>Protocols>SMTP>Defualt SMTP Virtual Server>Queues). I have sent a few test messages from inside the network and from my Yahoo account and none arrive in the mailbox and no bounce back.
I have poured over all the SMTP settings and the users mailbox settings, deleted and recreated the mailbox, and tested again and again. It feels like Iam missing something, but everything appears to be setup correctly. Any help or suggestions welcome.
.:TUCK:.