用PHP验证邮箱有效性

在sitepoint挖到一篇Verify a User’s Email Address Using PHP，本来打算自己翻译一下，学习一下。所以翻PHP Funtion查找当中出现的函数，无意中就发现checkdnsrr函数那里就有了更精妙的例子，分享给大家！

< ?php

function validate_email($email){

$exp = "^[a-z'0-9]+([._-][a-z'0-9]+)*@([a-z0-9]+([._-][a-z0-9]+))+$";

if(eregi($exp,$email)){ //先用正则表达式验证email格式的有效性

if(checkdnsrr(array_pop(explode("@",$email)),"MX")){//再用checkdnsrr验证email的域名部分的有效性
return true;
}else{
return false;
}

}else{

return false;

}
}

?>

注意：checkdnsrr函数在win主机上是无效的！！

Verify a User’s Email Address Using PHP中提出了另一种解决办法，写自己的函数：

function myCheckDNSRR($hostName, $recType = '')
{
if(!empty($hostName)) {
if( $recType == '' ) $recType = "MX";
exec("nslookup -type=$recType $hostName", $result);
// check each line to find the one that starts with the host
// name. If it exists then the function succeeded.
foreach ($result as $line) {
if(eregi("^$hostName",$line)) {
return true;
}
}
// otherwise there was no mail handler for the domain
return false;
}
return false;
}