Outlook Attachments And Winmail.dat

Mornings like this remind me why it’s great to work at Webmail.us: we like to get things done!   We decided that we had to have a feature on Friday morning.  It was in testing that afternoon.  It went on our system live over the weekend.  This morning our customers have a useful new feature.

Winmail.dat – Proprietary Outlook Attachment

This weekend we updated our Webmail product to automatically decode a winmail.dat attachment and break it into an RTF document (Word compatible) and into
any other attachments that may have existed inside the winmail.dat.
Here’s a little background info for those who want it:

When Outlook is configured to compose a message in Rich Text Format (RTF) it generates a file called winmail.dat, a specially encoded file with extra text color and formatting options.  Before HTML was widely used to compose email, RTF was the way to get nicer formatting.  But other email clients didn’t know how to read the special encoding.

Even worse, normal files attached to an RTF’d email were sometimes authomatically zipped up into the winmail.dat as well.  So an email sent from Outlook to Netscape Mail, Eudora, Mac Mail, etc. had this extra, useless attachment and no way to get at any other attachments that might have been sent.  But our Webmail client will now allow our customers to get at all of the RTF information & other attachments they need.

Open Source Community

For any of you who follow our open-source doings, we are releasing this code to the community.  There are another couple of important projects that we’re finishing up over the next week or two.  We’re even planning a new section on our website just for projects completed in-house to be released under the GPL.  I’m excited to blog about this more, but I’d better wait until we have at least one of those projects available for you to download!


Kirk Averett is the senior director of product for Cloud Office at Rackspace.


  1. Now I have 3 emails with webmail.dat attached that I cannot delete and continually come to my phone as new. As soon as I delete they come back. Logged directly into backspace I cannot get rid of these. Help


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