i am currently using this regex to validate email address using javascript /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/ now i want to allow users to enter multiple email addresses seperated by comma or semicolon so i made the javascript this way /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})(?:[,;]([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})*$/i; But it does not seem to work.. can anyone tell me whts wrong thanks