Pear mail - "Unable to authenticate to smtp server"

[saran_php]

Hi ,
I am trying to send mail using PEAR mail functionality.
I have used the following code snippet to send mails. But, when I execute the code I am getting "unable to authenticate to smtp server". I need this solved urgently. If any of you people give me your suggestions, it would be great !!!!!!!!.

<?php
require_once "Mail.php";

$from = "Sandra Sender <sender@example.com>";
$to = "Ramona Recipient <recipient@example.com>";
$subject = "Hi!";
$body = "Hi,\n\nHow are you?";

$host = "mail.example.com";
$username = "smtp_username";
$password = "smtp_password";

$headers = array ('From' => $from,
'To' => $to,
'Subject' => $subject);
$smtp = Mail::factory('smtp',
array ('host' => $host,
'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>");
}
?>

[mark]

[saran_php]

Yes, i have checked the credentials. They are the same.

[mark]

Where does this "unable to authenticate to smtp server" come from? I can't find it in the code.

Please make also sure that you have the latest version of Mail and Net_SMTP installed.