Have you ever received e-mail attachments named "winmail.dat" or "Part 1.2.1," or similarly named, inaccessible documents? What's up? Read on.

Microsoft Outlook allows its users to send mail in a non-standard rich text format known as TNEF. As a matter of fact, an Outlook user isn't explicitly told that they're sending TNEF, so they have no idea they're causing you any problem. As far as they're concerned, they're creating a more readable text message for you. You, on the other hand, receive an e-mail message with one or more mysterious attachments that you can't seem to open with any application you have.

The attachments are named "winmail.dat" or "Part 1.2.1" or something similar, and usually contain a TNEF formatted version of the message you received as plain text. Occasionally, however, there will be a document that is included in the winmail.dat file that you have no way to open.

So, what can you do when you receive one of these attachments? Here are some suggestions that may help.