Why are some of my email attachments winmail.dat files?

Email users sometimes find that they receive email messages with a strange file attached, called winmail.dat. When they attempt to open this file, either it can't be opened at all, or it contains "garbage" data.

The situation causing this is that people are using several different email client programs to receive, read, and send email. The most commonly used email client programs are Microsoft Outlook  and Thunderbird. Unfortunately, Outlook does not "play nice" with the other email programs all the time. This causes problems, not for the sender of the email, but the recipient, particularly when actual files are attached to messages.

When an Outlook user composes and sends a message using either Rich Text Format or HTML Format, Outlook generates a file, winmail.dat, and attaches it to the end of the message. winmail.dat contains formatting information, in a human-unreadable form, that Outlook will use on the receiving end to display this email message correctly. Unfortunately, Outlook is the ONLY email client program that can use this information! Thunderbird, and other email client programs don't understand this information.

The Solution:

Download Winmail.dat Reader from

http://www.kopf.com.br/winmail

Follow the online instruction to download this product. 

Other than this, there's not much you can do on your end to fix the problem, since it's not your email program generating the problem. If you just don't want to deal with the problem, the other approach is to reply to the individual who sent you the offending email and ask that they re-send the message, with the attached files, as a plain text message, not in Rich Text Format or HTML.