Multiple email addresses validation

 Hi, I'm trying to validate multiple email addresses in a textbox, it is working fine using the Regex:
^(\s*;?\s*[0-9a-zA-Z]([-.\w]*[0-9a-zA-Z])*@([0-9a-zA-Z][-\w]*[0-9a-zA-Z]\.)+[a-zA-Z]{2,9})+\s*$
 It is working fine, BUT when I enter many emails and there is an error in format of any email address of these, it will crash browser, javascript processing too long that on FF it informs me that a script is taking along time.
 I tried making validation on server side by using property 
EnableClientScript = false

But it takes along time on server side as well!
Is there anyway to validate on multiple email addresses format in a single textbox, any ideas ?? please help
 
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