PHP/PEAR Mail Not Sending as Text Message - php

Question

I'm working on a script that will send text messages via email (i.e. ####txt.att.net) and PHP's simple mail() function was not working. I could send email messages just fine through that method, but the texts were not being delivered. I did more research and found that carriers often block messages without a sender and using PEAR with SMTP is a better solution.
However, the following code works to send emails but is still not delivering AT&T text messages:
<?php
require_once "Mail.php";
$from = "XXX <XXX>";
$to = "XXX <XXX#txt.att.net>";
$subject = "Test email using PHP SMTP\r\n\r\n";
$body = "This is a test email message";
$host = "XXX";
$port = "26";
$username = "XXX";
$password = "XXX";
$headers = array (
'From' => $from,
'To' => $to,
'Subject' => $subject);
$smtp = Mail::factory('smtp',
array (
'host' => $host,
'port' => $port,
'auth' => true,
'username' => $username,
'password' => $password));
$mail = $smtp->send($to, $headers, $body);
if (PEAR::isError($mail)) {
echo("<p>" . $mail->getMessage() . "</p>");
} else {
echo("<p>Message successfully sent!</p>");
}
?>
Is it maybe an issue with headers not being formatted correctly, etc? Any ideas?

Answer 1

According to their example you do not need the new lines after the subject:
http://pear.php.net/manual/en/package.mail.mail.send.php
Check the AT&T response they might decline it if they have you blacklisted or you do not have a valid rDNS or other reasons.
They seem to experience a problem seeing the rDNS records of some IP's.
Use this it will tell you all the info you need.
http://wordpress.org/extend/plugins/xmail-the-right-way
Post the log of it here.