Had a nasty run-in with Outlook 2007 the other day: despite the internet message format being set to HTML, recipients not using Outlook would still receive mail with attachments as RTF with an unreadable winmail.dat file attached to it.



and



Clueless, I started poking around and finally resorted to Google to find out what was going on. Apparently, there is a separate setting per e-mail address in your contacts list, stating what format that recipient should be able to receive. By default, it is set to Let Outlook decide which basically tells to use the default in Outlook options (thus, being HTML).
However, this is also the choice of Always use RTF, which basically forces Outlook   ...