How to tell the difference between user-agent of outlook 2003(or earlier) and IE open?
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When I use webbug technique to track email opens and detect email client, I was able to tell the outlook version by user-agent string, but only for outlook 2007 and later. (by keycode MSOFFICE 12 and MSOFFICE 14)
When I look at the string for outlook 2003, and compare with the open on IE browser, it looks very similar.
Is there any keyword to tell the difference between those two user-agent strings?

Appreciate your help!