求助：QMAIL的Remote邮件队列出现大量反信造成邮件列表堵塞

ToToDoDo

邮件系统使用的是QMAIL

[root@server3 bin]# ./qmHandle -s
Messages in local queue: 1
Messages in remote queue: 856

用
./qmHandle -R
察看队列的内容，出现的邮件中99%都是如下这种failure notice

6327859 (7, R)
  Return-path:
  From: MAILER-DAEMON@mydomain.com
  To: phone@mailtree.org
  Subject: failure notice
  Date: 2 Sep 2007 04:38:01 -0000
  Size: 2863 bytes

6327721 (7, R)
  Return-path:
  From: MAILER-DAEMON@mydomain.com
  To: gergedmes@yahoo.co.jp
  Subject: failure notice
  Date: 2 Sep 2007 03:31:56 -0000
  Size: 2246 bytes

6328457 (7, R)
  Return-path:
  From: MAILER-DAEMON@mydomain.com
  To: okey@mailctrl.com
  Subject: failure notice
  Date: 2 Sep 2007 05:55:16 -0000
  Size: 3570 bytes

直接察看这种邮件的内容，都是类似如下本地找不到此用户的回复。

Received: (qmail 1973 invoked for bounce); 2 Sep 2007 06:10:07 -0000
Date: 2 Sep 2007 06:10:07 -0000
From: MAILER-DAEMON@mydomain.com
To: rrecur@hyip-hosting.net
Subject: failure notice

Hi. This is the qmail-send program at mail.mydomain.com.
I'm afraid I wasn't able to deliver your message to the following addresses.
This is a permanent error; I've given up. Sorry it didn't work out.

<col3678@mydomain.com>:
Sorry, no mailbox here by that name. vpopmail (#5.1.1)

--- Below this line is a copy of the message


虽然目前我是通过CRON脚本定时用qmHandle -Sfailure\ notice命令删除邮件队列中邮件名为failure notice的邮件。
但是感觉这方法不治本，请教各位有何高招？

ToToDoDo

SMTP阶段如何知道邮件来源的地址不存在呢？

ToToDoDo

请问具体实施的措施是？