Miscellany

$q=$_REQUEST["q"];
$result="";

function check_email_address($q) {
    // First, we check that there's one @ symbol, and that the lengths are right
    if (!ereg("^[^@]{1,64}@[^@]{1,255}$", $q)) {
        // Email invalid because wrong number of characters in one section, or wrong number of @ symbols.
        return false;
    }
    // Split it into sections to make life easier
    $email_array = explode("@", $q);
    $local_array = explode(".", $email_array[0]);
    for ($i = 0; $i < sizeof($local_array); $i++) {
        if (!ereg("^(([A-Za-z0-9!#$%&'*+/=?^_`{|}~-][A-Za-z0-9!#$%&'*+/=?^_`{|}~\.-]{0,63})|(\"[^(\\|\")]{0,62}\"))$", $local_array[$i])) {
            return false;
        }
    }
    if (!ereg("^\[?[0-9\.]+\]?$", $email_array[1])) { // Check if domain is IP. If not, it should be valid domain name
        $domain_array = explode(".", $email_array[1]);
            if (sizeof($domain_array) < 2) {
                return  false; // Not enough parts to domain
            }
            for ($i = 0; $i < sizeof($domain_array); $i++) {
                if (!ereg("^(([A-Za-z0-9][A-Za-z0-9-]{0,61}[A-Za-z0-9])|([A-Za-z0-9]+))$", $domain_array[$i])) {
                    return false;
                }
            }
        }
}


 if (strlen($q) > 0){

         $sql = "SELECT emaillist FROM emails WHERE emaillist='$q'";
 
         $result = mysql_query($sql); 
        $num = mysql_num_rows($result);
 
             {
 
                 if (check_email_address($q) != "false"){
                    if ($num == "0") {
                         $response=" Email is Available";
                    }
                 }
                else
                {
                $response=" Email is Already Registered or is Invalid";
                 }
             }
        }
 
echo $response;