I have Exchange Server 5.5 with mix clients (Outlook 97, 2000 & 2003). I have set the limit to 10MB at the server level. Our clients not running 2003 can receive attachments up to 10MB, but the 2003 clients can only receive up to 8MB. I have sent the exact same 8MB file to both types of clients. The 2000 client received it and the 2003 didn't. I have tested this with three 2003 clients; same results for all three. All were able to receive a 7MB file.