Email validation '+' not accepting I have written email validation as follow.

if($email != ''){
             if (!ereg("^[_a-zA-Z0-9]+(\.[_a-zA-Z0-9-]+)*@[a-zA-Z0-9-]+(\.[a-zA-Z0-9-]+)*(\.[a-zA-Z]{2,3})$",$email)) {
               form_set_error($email, t('Please enter a valid Email address.'));
             }
          }


But when i try to register with 'test.byme+1@gmail.com' , Not accepting with '+'. Can any one correct my code..Thanks
No need to reinvent the wheel: valid_email_address().