i just checked the HTTP_USER_AGENT for IE and it says

"Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; .NET CLR 1.1.4322)"

i wonder why it says mozilla in the begining??????
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Bhaskar GanapatheCommented:
Hi loving_chronic,

If you compare the User-Agent headers of IE and Firefox with those of microbrowsers, you will find that the User-Agent header of IE and Firefox contains the word "Mozilla" while those of microbrowsers do not. This can be served as a simple rule to determine whether a user agent is a web browser on a personal computer or a microbrowser on a mobile device.

Note that the above rule does not work in all cases. The User-Agent header of some microbrowsers also contains the word "Mozilla". For example, some Nokia 6630 cell phones use a "Mozilla compatible" User-Agent header. The reason is that Nokia 6630 is a web-compatible cell phone and can accept HTML content, but some websites that are designed for desktops will deny access to Nokia 6630 if the "Mozilla compatible" User-Agent header is not present.

"Mozilla compatible" User-Agent header of the Nokia 6630 cell phone:
Mozilla/4.0 (compatible; MSIE 5.0; Series60/2.8 Nokia6630/4.06.0 Profile/MIDP-2.0 Configuration/CLDC-1.1)

If you find the word "Mozilla" and the OS name "Windows NT" in the User-Agent string, it is almost certain that the user agent is a web browser on a computer but not on a mobile device; if you find the word "Mozilla" and the browser name "Firefox", it is certain that the user agent is a Firefox browser running on a computer since Firefox does not have a mobile device version (at the time of this writing).

That's a historical reason...

For what's happening you could read

under "User agent spoofing", 2nd paragraph.

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loving_chronicAuthor Commented:
you mean to say that the server responds with HTML in case of "mozilla" else xHTML
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