Unable to send mail in PHP.

[Arvind_Reloaded]

I was sending mails to my customers using php . Everything was fine till last week all of a sudden the mail script is not working and this is the error message I am receiving

"Warning: mail() [function.mail]: SMTP server response: 553 sorry, that domain isn't allowed to be relayed thru this MTA (#5.7.1)"

Assuming this has to be some authentication issue as I was using from as my gmail account.

So I tried a new script


<?php
require_once "Mail.php";

$from = "Sandra Sender <XXXX@gmail.com>";
$to = "Ramona Recipient <XXXXX@yahoo.com>";
$subject = "Hi!";
$body = "Hi,\n\nHow are you?";

$host = "smtp.gmail.com";
$username = "XXXX@gmail.com";
$password = "XXXXXX";

$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>");
}
?>

I am receiving a following error for this new authenticating script

Failed opening required 'Mail.php' (include_path='.\;C:\Program Files\HSphere\3rdparty\PHP\PHP4\PEAR')

Seeing the error i am assuming the pear mail script is not installed in my server. How should I install the script. I am in shared hosting so can i do this or my hosting company will do this.

In a great trouble because of this as this is business critical.Please help me sort out this.

[buldozerce]

http://phpmailer.sf.net

[SituationSoap]

Mail is a built in PHP function. You shouldn't need to include a script to get it to function.