Attachement not accessible Winmail.dat When viewing a message with an attachment in Express, at times the attachement is given the name winmail.dat This document describes why that happens and what you can do to help address this issue. The filename of an attachment is reported in the header of a message in the Content-Disposition in a RFC compatible formated message. Rich Text messages do not follow that format and the result is an associated description for the attachment entitled winmail.dat Below is an sample header of a message from AOL: >>> >>>------=_NextPart_000_0062_01C30346.2044F510 >>>Content-Type: message/rfc822 >>>Content-Transfer-Encoding: 7bit >>>Content-Disposition: attachment In order for Express to provide the filename as the attachment link the content disposition must include a filename="(and the name for the file here) So the correct header should be: >>>------=_NextPart_000_0062_01C30346.2044F510 >>>Content-Type: message/rfc822 >>>Content-Transfer-Encoding: 7bit >>>Content-Disposition: attachment; filename="yourdocument.doc" Notice that the filename=" " is present above. Express uses the value presented here to display the attachment name. If it is not present then the attachments will be automatically be renamed to "unknown.unk". Which is the Link (unk) to the message's unknown/unnamed attachement. Desktop email clients such as Outlook can use a different method to retrieve the attachment name, therefore you will not see this issue there. When you find a message from a service, such as AOL, that does not support this feature please write postmaster of the domain in question and ask that they support this feature.