PHP function to check valid email addresses

Below you will find a small useful function on PHP that uses regular expressions to find out if a provided email address has a valid format or not.

<?PHP

function correctemail($emailtocheck) {

    if (! preg_match( '/^[A-Za-z0-9!#$%&\'*+-/=?^_`{|}~]+@[A-Za-z0-9-]+(\.[A-Za-z0-9-]+)+[A-Za-z]$/', $emailtocheck)) {

            return false;

    } else {

        return true;

    }

}

?>

The script wont check for valid domains but for RFC compliant type addresses, all in all you could combine this function with one that checks if a provided domain under an email is valid and that should do the trick.