how to find weather an email address exi

[shams]

how can i find that a specific email address exist or not in any given server name.for examle i give an email address [e-mail] then the application will check weather this email address exist or not in yahoo server.
if any body has idea then plz tell me

[mattw]

Check this article on Zend on email validation:

http://www.zend.com/zend/spotlight/ev12apr.php

Matt Wade
codewalkers.com