winmail.dat. Does reading those words give you the beginnings of heartburn? Those who regularly trade email with Windows users are all too familiar with winmail.dat files, which are email attachments that can contain essential aspects of the email communication. Email generated by Outlook for Windows can create winmail.dat attachments for a variety of reasons. It may just be to include the RTF version of the message you can see as plain text. But winmail.dat might also contain an important attachment, such as an image, a calendar invitation, an address book contact, or nested messages.
To decode winmail.dat files, you need special software, and the easiest approach is with Creative in Austria’s Letter Opener for macOS Mail. Once installed, Mail in macOS automatically decodes winmail.dat files and displays their contents natively within Mail. It’s as easy as that.