Hi How does the new Exchange 2003 SP1 OWA attachment registry entry 'KnownContentTypes' work with the other registry entries for blocking attachments in OWA. Does this new entry take precedent, or is it cumulative. Also will the OWA Web Admin be changed to handle this? MS KB 873138 and 555001. Question is if I only allow types of .txt and .doc in the level1 and level2 categories, would it stop an executable file being attached.? As one can rename the executable with an extension of .txt and OWA accepts it as an attachment. Thanks RajiA Email disclaimer: This email and any attachments are confidential. If you are not the intended recipient, do not copy, disclose or use the contents in any way. If you receive this message in error, please let us know by return email and then destroy the message. Environment Bay of Plenty is not responsible for any changes made to this message and/or any attachments after sending. ****************************************************** This e-mail has been checked for viruses and no viruses were detected.