How Can I Get Phpmailer Mailings to Send Message With a return-path to Another Domain

I'm using a 3rd party SMTP service for sending my newsletters. Because of that, my ISP does not accept bounces because they are coming from an email not originating with them. Okay. So I set up a mailbox with my SMTP service to accept the bounces.

However, my mailing list program is refusing to send out emails whose return-path has a different domain than the from field.

I believe this is caused by phpmailer in it's mailsend routine:

The key code appears to be this, but I'm not that much of an expert with PHP to figure out how to get around whatever check it is doing, which I think has something to do with that safe_mode. The return-path value that I want to use is in the variable: $this->Sender

  /** 
   * Sends mail using the PHP mail() function. 
   * @param string $header The message headers 
   * @param string $body The message body 
   * @access protected 
   * @return bool 
   */ 
  protected function MailSend($header, $body) { 
    $toArr = array(); 
    foreach($this->to as $t) { 
      $toArr[] = $this->AddrFormat($t); 
    } 
    $to = implode(', ', $toArr); 
    $params = sprintf("-oi -f %s", $this->Sender); 
    if ($this->Sender != '' && strlen(ini_get('safe_mode'))< 1) { 
      $old_from = ini_get('sendmail_from'); 
      ini_set('sendmail_from', $this->Sender); 
      if ($this->SingleTo === true && count($toArr) > 1) { 
        foreach ($toArr as $key => $val) { 
          $rt = @mail($val, $this->EncodeHeader($this->SecureHeader($this->Subject)), $body, $header, $params);
           // implement call back function if it exists 
          $isSent = ($rt == 1) ? 1 : 0; 
          $this->doCallback($isSent,$val,$this->cc,$this->bcc,$this->Subject,$ body);
         } 
      } else { 
        $rt = @mail($to, $this->EncodeHeader($this->SecureHeader($this->Subject)), $body, $header, $params);
         // implement call back function if it exists 
        $isSent = ($rt 开发者_Python百科== 1) ? 1 : 0; 
        $this->doCallback($isSent,$to,$this->cc,$this->bcc,$this->Subject,$b ody);
       } 
    } else { 
      if ($this->SingleTo === true && count($toArr) > 1) { 
        foreach ($toArr as $key => $val) { 
          $rt = @mail($val, $this->EncodeHeader($this->SecureHeader($this->Subject)), $body, $header, $params);
           // implement call back function if it exists 
          $isSent = ($rt == 1) ? 1 : 0; 
          $this->doCallback($isSent,$val,$this->cc,$this->bcc,$this->Subject,$ body);
         } 
      } else { 
        $rt = @mail($to, $this->EncodeHeader($this->SecureHeader($this->Subject)), $body, $header);
         // implement call back function if it exists 
        $isSent = ($rt == 1) ? 1 : 0; 
        $this->doCallback($isSent,$to,$this->cc,$this->bcc,$this->Subject,$b ody);
       } 
    } 
    if (isset($old_from)) { 
      ini_set('sendmail_from', $old_from); 
    } 
    if(!$rt) { 
      throw new phpmailerException($this->Lang('instantiate'), self::STOP_CRITICAL);
     } 
    return true; 
  }

Does anyone know what in this code is preventing me from using a different domain for my return-path, or better yet, does anyone know how I can fix (or hack) this so it will send out my mail?

@Sanmai's comment got me looking at the parameters. When I started testing some of them in the phpmailer routine, I found the code wasn't executed. So at least he helped me realize the problem's somewhere else.

I still have the problem. I'll now try to better isolate it. Then maybe I can solve it, and if not, I'll modify this question and try again.

Thanks for giving me a bit of something to go on.

What error are you getting? It could be that the mailer server you are using doesn't allow different return address domains to prevent their service being used to send spam.