收到以下内容的退信,请帮忙分析原因,不胜感激!

longforcn

The attached message had PERMANENT fatal delivery errors!<br>
<br>
After one or more unsuccessful delivery attempts the attached message has<br>
been removed from the mail queue on this server. The number and frequency<br>
of delivery attempts are determined by local configuration parameters.<br>
<br>
YOUR MESSAGE WAS NOT DELIVERED TO ONE OR MORE RECIPIENTS!<br>
<br>
Failed address: shiro-m@dc5.so-net.ne.jp<br>
<br>
--- Session Transcript ---<br>MX-record resolution of [dc5.so-net.ne.jp] in progress (DNS Server: 127.0.0.1)...<br>P=100 D=dc5.so-net.ne.jp TTL=(60) MX=[mxin2.ms.so-net.ne.jp] {202.238.83.12}<br>P=100 D=dc5.so-net.ne.jp TTL=(60) MX=[mxin1.ms.so-net.ne.jp] {202.238.83.11}<br>Attempting MX: P=100 D=dc5.so-net.ne.jp TTL=(60) MX=[mxin1.ms.so-net.ne.jp] {202.238.83.11}<br>Attempting SMTP connection to [202.238.83.11 : 25]<br>Waiting for socket connection...<br>Socket connection established<br>Waiting for protocol initiation...<br>Attempting MX: P=100 D=dc5.so-net.ne.jp TTL=(60) MX=[mxin2.ms.so-net.ne.jp] {202.238.83.13}<br>Attempting SMTP connection to [202.238.83.13 : 25]<br>Waiting for socket connection...<br>Socket connection established<br>Waiting for protocol initiation...<br>30 second wait for protocol timeout exceeded.<br>Attempting to send message to gateway.<br>Attempting SMTP connection to [mail.3dl.com : 25]<br>A-record resolution of [mail.3dl.com] in progress (DNS Server: 127.0.0.1)...<br>D=mail.citsdl.com TTL=(21) A=[211.99.188.11]<br>Attempting SMTP connection to [211.99.188.11 : 25]<br>Waiting for socket connection...<br>Socket connection established<br>Waiting for protocol initiation...<br>220 ESMTP on WinWebMail [3.6.3.1] ready. <a target=_blank href=http://www.winwebmail.com>http://www.winwebmail.com</a><br>EHLO 3dl.com<br>250-SIZE<br>250 AUTH LOGIN<br>MAIL From:<japan@3dl.com> SIZE=36128<br>250 OK<br>RCPT To:<shiro-m@dc5.so-net.ne.jp><br>550 Local user only or Authentication mechanism<br>QUIT<br>
--- End Transcript ---<br>
<br>
: Message contains [1] file attachments<br>

jenbabe

对方的地址无效　　Failed address: shiro-m@dc5.so-net.ne.jp<br>

longforcn

但却收到了来自这个地址的EMAIL呀<br>

jia_william

系统首先试图将邮件直接投递到对方的邮件服务器，可能是由于线路原因或者其他与双方通讯有关的原因，造成不能直接投递。<br>
然后，系统试图通过SMTP网关发送该邮件，因此出现了如下的信息<br>
Attempting to send message to gateway.<br>Attempting SMTP connection to [mail.3dl.com : 25]<br>
但是，估计该SMTP主机做了一些发送限制，造成<br>550 Local user only or Authentication mechanism<br>