php 正则表达式验证电子邮件是否正确

function checkemail($email)
{
 $regular='/^[_.0-9a-z-a-z-]+@([0-9a-z][0-9a-z-]+.)+[a-z]{2,4}$/';
 if(preg_match($regular,$email))
 {
  $message=1;
 }
 else
 {
  $message=0;
 }
 return $message;
}