PEAR Mail, Mail_Mime and headers() overwrite - email

Question

I'm currently working on a reminder PHP Script which will be called via Cronjob once a day in order to inform customers about smth.
Therefore I'm using the PEAR Mail function, combined with Mail_Mime. Firstly the script searches for users in a mysql database. If $num_rows > 0, it's creating a new Mail object and a new Mail_mime object (the code encluded in this posts starts at this point). The problem now appears in the while-loop.
To be exact: The problem is
$mime->headers($headers, true);
As the doc. states, the second argument should overwrite the old headers. However all outgoing mails are sent with the header ($header['To']) from the first user.
I'm really going crazy about this thing... any suggestions?
(Note: However it's sending the correct headers when calling $mime = new Mail_mime() for each user - but it should work with calling it only once and then overwriting the old headers)
Code:
// sql query and if num_rows > 0 ....
require_once('/usr/local/lib/php/Mail.php');
require_once('/usr/local/lib/php/Mail/mime.php');
ob_start();
require_once($inclPath.'/email/head.php');
$head = ob_get_clean();
ob_start();
require_once($inclPath.'/email/foot.php');
$foot = ob_get_clean();
$XY['mail']['params']['driver'] = 'smtp';
$XY['mail']['params']['host'] = 'smtp.XY.at';
$XY['mail']['params']['port'] = 25;
$mail =& Mail::factory('smtp', $XY['mail']['params']);
$headers = array();
$headers['From'] = 'XY <service#XY.at>';
$headers['Subject'] = '=?UTF-8?B?'.base64_encode('Subject').'?=';
$headers['Reply-To'] = 'XY <service#XY.at>';
ob_start();
require_once($inclPath.'/email/templates/files.mail.require-review.php');
$template = ob_get_clean();
$crfl = "\n";
$mime = new Mail_mime($crfl);
while($row = $r->fetch_assoc()){
$html = $head . $template . $foot;
$mime->setHTMLBody($html);
#$to = '=?UTF-8?B?'.base64_encode($row['firstname'].' '.$row['lastname']).'?= <'.$row['email'].'>'; // for testing purpose i'm sending all mails to webmaster#XY.at
$to = '=?UTF-8?B?'.base64_encode($row['firstname'].' '.$row['lastname']).'?= <webmaster#XY.at>';
$headers['To'] = $to; // Sets to in headers to a new
$body = $mime->get(array('head_charset' => 'UTF-8', 'text_charset' => 'UTF-8', 'html_charset' => 'UTF-8'));
$hdrs = $mime->headers($headers, true); // although the second parameters says true, the second, thrid, ... mail still includes the To-header form the first user
$sent = $mail->send($to, $hdrs, $body);
if (PEAR::isError($sent)) {
errlog('error while sending to user_id: '.$row['id']); // personal error function
} else {
// Write log file
}
}

Answer 1

There is no reason to keep the old object and not creating a new one.
Use OOP properly and create new objects - you do not know how they work internally.