急。邮件服务器上很多用户每天都会收到很多退信，多的达到几百封，服务器快无法使用了。就是象这样的，邮件。发件人： MAILER-DAEMON发送时间： 2011-03-21 11:03:43收件人： zyq抄送： 主题： Undelivered Mail Returned to Sender This is the mail system at host mx2-197.sinamail.sina.com.cn.I'm sorry to have to inform you that your message could notbe delivered to one or more recipients. It's attached below.For further assistance, please send mail to postmaster.If you do so, please include this problem report. You candelete your own text from the attached returned message.                   The mail system<xiao5788@mail3-112.sinamail.sina.com.cn> (expanded from <xiao5788@sina.com>):    host mail3-112i.sinamail.sina.com.cn[10.55.2.112] said: 522 5.2.2 can not    find the user path (in reply to end of DATA command)Reporting-MTA: dns; mx2-197.sinamail.sina.com.cnX-Postfix-Queue-ID: 47CCA29B1E6X-Postfix-Sender: rfc822; zyq@byg.net.cnArrival-Date: Mon, 21 Mar 2011 11:08:22 +0800 (CST)Final-Recipient: rfc822; xiao5788@mail3-112.sinamail.sina.com.cnOriginal-Recipient: rfc822;xiao5788@sina.comAction: failedStatus: 5.2.2Remote-MTA: dns; mail3-112i.sinamail.sina.com.cnDiagnostic-Code: smtp; 522 5.2.2 can not find the user path------------------------------------------------------------From: