This issue is most common when Microsoft Outlook is used to send email. Email messages sent from Outlook in RTF (rich text format) may include formatting commands that cannot be read by other email client programs. When this happens, the rich text formatting commands get placed into a winmail.dat file attachment.

If you have received an email message with a winmail.dat file attached, fortunately there are several online winmail.dat viewers that you can use to decrypt those pesky winmail.dat attachments and obtain the original files and email message. The following third party websites provide tools for opening winmail.dat attachments:

http://www.winmaildat.com/
http://download.cnet.com/Winmail-Opener/3000-2369_4-10477142.html
http://email.about.com/od/macosxmailaddons/gr/omic.htm
http://www.macworld.com/article/140429/2009/05/letteropener.html

If you are the sender, you can resolve your winmail.dat dilemma by ensuring your email client does not send email using RTF. Instructions for Microsoft Outlook are provided below:

Click on the Tools menu and select Options.

Next to "Compose in this message format," select either HTML or Plain Text. HTML is the default value. I recommend using HTML if you send email messages that contain embedded images or external website content.

Click on Internet Format.

Below "When sending Outlook Rich Text Messages to Internet receipients, use this format:" select either Convert to HTML format or Convert to Plain Text format.

Click OK.

Click Apply and then click OK.

Messages will no longer be sent in Rich Text Format and your recipients should no longer receive winmail.dat attachments.

Outlook allows users to override the default settings for specific contacts. If one or more of your contacts continue to receive winmail.dat attachments with your messages, right-click on the recipient's email address and click on Properties. If you do not see a Properties option, look for Outlook Properties.

In the Internet format: list, select "Let Outlook decide the best sending format".

Click OK.

You can do further research on the winmail.dat issue by clicking on the following links:

Microsoft Support Article
About.com Article
Apple Support Article
__________________________________________________________

Join us on Facebook: http://about.hover.com/facebook

__________________________________________________________

Article Shortcut: http://about.hover.com/winmaildat

__________________________________________________________