<A target="_blank" href="http://www.bleedyellow.com/blogs/NotesShop/entry/are_you_still_having_winmail_dat_issues7?lang=en_us">Jalpresh Tailor was surprised to learn some people are still getting this error. </A>There's a Notes.ini setting you can use for some older versions of Notes or Jalpresh has provided a link to an OpenNTF solution.