I have a user with a problem with email attachments. If this specific user (say User-A at Site-A) sends emails to User-B at Site-B the attachments are stripped. If User-A uses OWA to send the same email with the same attachment it works correctly. When User-B gets the email there are no warnings from the Firewall, SPAM filter, or Virus Scanner indicating that an attachment was removed. This leads me me to believe that the attachment was already missing before it ever left Site-A. I think that there is something in the installation/configuration of Outlook for User-A that is causing the problem, but I'm stumped. Site-A recently went through a domain migration and Exchange upgrade simultaneously, so there are plenty of potential culprits. What is really strange is that if User-A sends the exact same email to a different user at Site-B the attachment comes through.
I'm just hoping that someone has an idea that I haven't thought of yet.