The WinMail.dat attachment indicates the sender sent a secure message using Microsoft Outlook set to Rich Text Format (RTF). The Secure Message Center does not support this proprietary Microsoft format. The sender will need to resend the message with Outlook set to HTML or Plaintext.

Please note: This RTF setting can be set in multiple places within Outlook and Exchange. Please refer to the 'Help' for your version of Outlook/Exchange.

The below links from Microsoft also has additional details:

http://support.microsoft.com/kb/138053

http://support.microsoft.com/kb/278061

Below are a few locations where this setting can be selected:

Outlook:

•             This can be set for all emails within Outlook's mail options.

•             This can also be used if Outlook is configured to reply using the same format in which the original email was received.

•             This can be set on a per recipient basis in Outlook's address book.

Exchange:

•             Exchange also has a setting to send all emails in Rich Text Format.