Exchange 2003 Server, users can send attached email's but can't receive them (they don't even receive the email. This was working for more than 4 years, nothing changed, from what I can tell. I did change the Message delivery under the Exchange 2003 Global Setting just to troubleshoot this issue. I updated the defaults to say Sending & Receiving message size to no limit
Receipient limit to no limit.
There are only 15 mailboxes on system. All can send attached email's, but none can receive. When someone from the outside of domain, or inside of domain sends an attached email, the Receipient inside of the domain will not receive the email at all. But if I send the person at the company an email with out an attachment, they will receive the email