这个问题是因为那些原因呢？

leeyongle

Mon 2008-03-24 20:17:21: ----------
Mon 2008-03-24 20:17:25: Session 4841; child 5; thread 1252
Mon 2008-03-24 20:05:15: Accepting SMTP connection from [218.193.144.119 : 48750]
Mon 2008-03-24 20:05:15: --> 220 jxsilk.cn ESMTP MDaemon 8.1.5; Mon, 24 Mar 2008 20:05:15 +0800
Mon 2008-03-24 20:06:01: <-- HELO mailgw.dhu.edu.cn
Mon 2008-03-24 20:06:01: --> 250 jxsilk.cn Hello mailgw.dhu.edu.cn, pleased to meet you
Mon 2008-03-24 20:06:02: <-- MAIL FROM: <[email=A@Y]A@Y[/email]>
Mon 2008-03-24 20:06:02: Performing IP lookup (dhu.edu.cn)
Mon 2008-03-24 20:06:02: *  D=dhu.edu.cn TTL=(1198) A=[218.193.144.119]
Mon 2008-03-24 20:06:02: ---- End IP lookup results
Mon 2008-03-24 20:06:02: --> 250 <[email=A@Y]A@Y[/email]>, Sender ok
Mon 2008-03-24 20:06:03: <-- RCPT TO: <[email=B@X]B@X[/email]>
Mon 2008-03-24 20:06:03: --> 250 <[email=B@X]B@X[/email]>, Recipient ok
Mon 2008-03-24 20:06:07: <-- DATA
Mon 2008-03-24 20:06:07: Creating temp file (SMTP): d:\mdaemon\queues\temp\md50001035140.tmp
Mon 2008-03-24 20:06:07: --> 354 Enter mail, end with <CRLF>.<CRLF>
Mon 2008-03-24 20:17:25: Connection timed out!
Mon 2008-03-24 20:17:25: SMTP session terminated (Bytes in/out: 24730/245)

连接超时，发送进程被中止...主要可能是哪些原因造成的呢？