A function to check if an email address is valid, which also includes a DNS look-up to check that the domain name is valid.
function isemail($email) { if (preg_match('/^\w[-.\w]*@(\w[-._\w]*\.[a-zA-Z]{2,})$/', $email, $matches)) { if (function_exists('checkdnsrr')) { if (checkdnsrr($matches[1] . '.', 'MX')) return true; // If a 'mail exchange' record exists if (checkdnsrr($matches[1] . '.', 'A')) return true; // Mail servers can fall back on 'A' records } else { return true; // For Windows } } return false;}
Please note that in some environments, like on the Windows OS, you might find that the DNS look-up is ignored, or might take a few seconds to time-out... so please test thoroughly.
Any feedback would be greatly appreciated. If you would like to use this code, please read the licence it is released under.