How PHP implements a method code that determines whether a mailbox is valid

This article brings you the content is about how PHP to determine whether the mailbox is valid method code, has a certain reference value, the need for a friend can refer to, I hope you have some help.

function Validate_email ($email) {    $exp = "^[a-z ' 0-9]+ ([. _-][a-z ' 0-9]+) *@ ([a-z0-9]+ ([. _-][a-z0-9]+)] +$";    if (eregi ($exp, $email)) {//Use regular expressions to verify the validity of the email format (        checkdnsrr (Array_pop (Explode ("@", $email), "MX")) {// Then use CHECKDNSRR to verify the validity of the domain name portion of the email            return true;        else{            return false;        }    } else{        return false;    }}

Note: The CHECKDNSRR function is not valid on the win host! Here is a foreign programmer proposed a solution, in addition to write a function to replace the CHECKDNSRR function:

function MYCHECKDNSRR ($hostName, $recType = ") {    if (!empty ($hostName)) {        if ($recType = =") $recType = "MX";            EXEC ("nslookup-type= $recType $hostName", $result);        foreach ($result as $line) {            if (eregi ("^ $hostName", $line)) {                return true;            }        }       return false;    }    return false;}