Running Exchange 2010 SP1 with most users using Outlook 2007 or 2010. Starting to hear complaints about users receive more WINMAIL.DAT files from external senders only. There are no reports our users are sending WINMAIL.DAT files, they only receive them from some external users.
Looking at the path the messages take, when checking the Spam gateway the message arrives with a WINMAIL.DAT as the attachment for some users, others receive the correct attachment. I have been unable to find any fix that can be made when our users receive a WINMAIL.DAT file, each time the Spam Gateway shows the attachment arriving as a WINMAIL.DAT file.
Reading posts and different articles the issue appears to be a sender format encoding issue and there is nothing that can be done on the receiving end. The issue is on a per recipient basis, others can receive the file correctly with one recipient receiving the incorrectly formatted message. Talking to the various sending organizations they are also running various versions of Exchange and Outlook.
Thank you for any information someone may have on the subject.