*  If you are using Windows, you need to use the smtp_message_class to set the return-path address.
 */
if (defined("PHP_OS") && strcmp(substr(PHP_OS, 0, 3), "WIN")) {
    $email_message->SetHeader("Return-Path", $error_delivery_address);
}
$email_message->SetEncodedEmailHeader("Errors-To", $error_delivery_address, $error_delivery_name);
$email_message->SetEncodedHeader("Subject", $subject);
/* If you are not going to personalize the message body for each recipient,
 * set the cache_body flag to 1 to reduce the time that the class will take
 * to regenerate the message to send to each recipient */
$email_message->cache_body = 0;
$message = "Hello,\n\nThis message is just to let you know that Manuel Lemos' e-mail sending class is working as expected for sending personalized messages.\n\nThank you,\n{$from_name}";
/* Create empty parts for the parts that will be personalized for each recipient. */
$email_message->CreateQuotedPrintableTextPart($message, "", $text_part);
/* Add the empty part wherever it belongs in the message. */
$email_message->AddPart($text_part);
/* Iterate personalization for each recipient. */
for ($recipient = 0; $recipient < count($to); $recipient++) {
    /* Personalize the recipient address. */
    $to_address = $to[$recipient]["address"];
    $to_name = $to[$recipient]["name"];
    $email_message->SetEncodedEmailHeader("To", $to_address, $to_name);
    /* Do we really need to personalize the message body?
     * If not, let the class reuse the message body defined for the first recipient above.
     */
    if (!$email_message->cache_body) {
        /* Create a personalized body part. */
        $message = "Hello " . strtok($to_name, " ") . ",\n\nThis message is just to let you know that Manuel Lemos' e-mail sending class is working as expected for sending personalized messages.\n\nThank you,\n{$from_name}";
        $email_message->CreateQuotedPrintableTextPart($email_message->WrapText($message), "", $recipient_text_part);
        /* Make the personalized replace the initially empty part */
        $email_message->ReplacePart($text_part, $recipient_text_part);