PHP正则验证邮箱格式是否正确

class isEmail{
     public function run($email){                    
        if(ereg("^([a-zA-Z0-9_-])+@([a-zA-Z0-9_-])+(.[a-zA-Z0-9_-])+",$email)){        
            return true;                         
        }else{                                
            return false;                         
        }                    
     }
}
$isEmail=new isEmail;
if($isEmail->run("going")==false){     
          echo "email is wrong";
}