It’s been at least a year since I’ve received an email with a winmail.dat file as an attachment. Winmail.dat and MSG files are created when someone using Microsoft Outlook adds special formatting, such as bolded text or fancy fonts, to an email message. Outlook, assuming that everyone knows how to read its special formatting, puts it all into a tidy little package that Apple’s Mail app (and many other email applications) can’t read. Klammer (Mac App Store link) helps you unpackage those files so you can get to the important content that is wrapped up inside them.
Klammer is a bit of a one trick pony, but it’s a pretty good trick. When you come across one of these files, you can open it in and use Klammer to read what’s in the file. The application also offers you the option of exporting the file in a format that can be read and imported by most email applications. An optional $10 in-app purchase takes batches of these files and, instead of converting them one at a time, allows you to convert them all in one shot.
Klammer is very good at what it does, but its value depends largely on how many files like these you have to open on a regular basis. (Take note that I said I’ve seen one in the last year.) If you have many of these files to convert, then Klammer may be just the ticket. If you, like me, rarely see these files, have a look at Josh Jacob’s free TNEF Enough or one of the other free Web-based converters.