有關Exchange server 5.5請大家幫幫忙

請問如果Exchange Sever 5.5要傳送email到AOL
好像不行,其錯誤訊息如下:

Your message

To: [email][email protected][/email]
Subject: FW: two images
Sent: Thu, 13 Sep 2001 09:01:36 +0800

did not reach the following recipient(s):

[email][email protected][/email] on Thu, 13 Sep 2001 09:01:40 +0800
?????????
The MTS-ID of the original message is: c=tw;a= ;p=mail;l=MAIL0109130101SY1WHQJP
MSEXCH:IMS:ELEVATION:HI-BIKE:MAIL 0 (000C05A6) Unknown Recipient

請問一下,,這個是什麼原因呢.
是不是MTA與AOL的郵件伺服器不能溝通呢..
請大家提供一點議見..