php邮箱验证的正则表达式代码

php邮箱验证的正则表达式，如下：

<?php
/**
* 邮箱地址正则表达式
* edit www.jb200.com
*/
$preg = '/^(w{1,25})@(w{1,16})(.(w{1,4})){1,3}$/';
$b = 'ffgddayasdadasdf@gmialsdfsdfasd3.com.cn.org';
if(preg_match($preg, $b)){
echo "匹配到了";
}else{
echo "没有匹配到";
}

//邮箱正则验证 示例2
if (ereg(“/^[a-z]([a-z0-9]*[-_.]?[a-z0-9]+)*@([a-z0-9]*[-_]?[a-z0-9]+)+[.][a-z]{2,3}([.][a-z]{2})?$/i; ”,$email)){ 
   echo “Your email address is correct!”;} 
else{ 
   echo “Please try again!”; 
} 

//邮箱正则验证 示例3
function checkEmail($email)
{
    $pregEmail = "/([a-z0-9]*[-_.]?[a-z0-9]+)*@([a-z0-9]*[-_]?[a-z0-9]+)+[.][a-z]{2,3}([.][a-z]{2})?/i";
    return preg_match($pregEmail,$email);  
}
?>