Hi, We are running Exchange 5.5 on NT4.0. We have a client who is sending .rtf files as an attachment to emails. When they send these the following happens: 1) IF the receiving email address is setup in Exchange (either an internal or external address), everything is received fine 2) IF the receiving email address is NOT setup in exchange the file is received as an unreadable .dat file. I understand that this is the information that is pulled off the original email and is generally formatting information that cannot be used by the receiving client. What I can't understand is WHY does the fact that the address is setup in Exchange matter or make a difference at all? If anyone can offer ANY advice at all about this, it is greatly appreciated. Thanks in advance Regards Troy Disclaimer: The information in this electronic mail message together with any attachments is confidential. It is intended solely for the addressee. Access to this Internet electronic mail message by anyone else is unauthorised. If you are not the intended recipient, any disclosure, copying, distribution or any action taken or omitted to be taken in reliance on it is prohibited and may be unlawful. Linfox accepts no responsibility for any effects this email message or attachments has on the recipient network or computer system.