I have a client using Entourage mail client on a Mac and he couldn't receive any attachment sent from Outlook. It appears as winmail.dat. This problem couldn't be fixed if we ask everything to change the mail format to "Plain Text" before sending out.
Is there any solution on MAC to read winmail.data ? Alternatively, will there be any solution on Exchange 2007 or 3rd tool that could explicity convert the mail format to plain text for particular user ?