某几个客户的邮件为什么总是发不进来？

bqj

公司的电脑用Merak架设了EMAIL服务器，邮件发送都已经正常。但有几个客户发的邮件总发不进来，客户那面收到了退回的邮件。检查邮件服务器的记录，相应的信息如下：<br>
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193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:36 +0800 Connected<br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:36 +0800 >>> 220 dalianemail.com ESMTP Merak 7.5.2; Fri, 17 Dec 2004 02:00:36 +0800<br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:37 +0800 <<< HELO dswu82.btconnect.com<br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:37 +0800 >>> 250 dalianemail.com Hello dswu82.btconnect.com [193.113.154.22], pleased to meet you.<br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:47 +0800 <<< MAIL FROM:<gilles@darwinauto.com><br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:47 +0800 >>> 250 2.1.0 <gilles@darwinauto.com>... Sender ok<br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:47 +0800 <<< RCPT TO:<admin@dalianemail.com><br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:47 +0800 >>> 250 2.1.5 <admin@dalianemail.com>... Recipient ok<br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:48 +0800 <<< DATA<br>
193.113.154.22 [00001E9C] Fri, 17 Dec 2004 02:00:48 +0800 >>> 354 Enter mail, end with "." on a line by itself<br>
SYSTEM [00001E9C] Fri, 17 Dec 2004 02:05:48 +0800 Disconnected<br>
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好象DATA并没有真正开始传送就停在那儿了，过了5分钟没有响应，对话被EMAIL服务器系统中止。<br>
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大家帮助分析一下，是什么原因？（这个客户发送我当地电信的邮箱却是正常的！）