checkdnsrr doesn't work for all?

[jackvull]

Hi
I use these 2 functions to check for correct email addresses.
However, I have put in a few email addresses that I know exist and work and the functions return false.
Any ideas on why this might happen? Should I be checking records other than MX?

function validateEmailOnLinux($email)
{
// take a given email address and split it into the
// username and domain.
list($userName, $mailDomain) = split("@", $email);
$flag = checkdnsrr($mailDomain.'.', "MX");
return $flag;
}

function validateEmailOnWindows($email)
{
list($userName, $hostName) = split("@", $email);
$recType = '';
if(!empty($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;
}

[Romeo]

The SMTP mail stuff works on MX records, if MX records are there. If no MX record can be found, a domain's A record will be tried.

Kind regards,
R.

[eeek]

This will also fail with temporary DNS outages. Do you really want to reject the user because you can't reach his DNS server?

[jackvull]

So, you recommend just using a regular expression or something and perhaps validating their address via a return email?

[eeek]

Yes, verify by actually sending an email.