Undeliverable message error

[Guest]

To whom it may concern,
No one within my organization can send an email to a specific organization.
The following bounce back error message returns (NOTE: it takes almost 24
hours to return back).

Your message did not reach some or all of the intended recipients.

Subject: Test Message
Sent: 12/2/2004 2:39 PM

The following recipient(s) could not be reached:

(e-mail address removed) on 12/4/2004 3:59 PM
The recipient was unavailable to take delivery of the message
The MTS-ID of the original message is: c=US;a=
;p=JEFFX;l=JXDOCSRVR-041202193830Z-399
MSEXCH:IMS:JEFFX:JXDOCSRVR:JXDOCSRVR 3499 (000B09AA) Host
unreachable

I've called the receiving organization and they say it is not them. They say
they are not rejecting our IP address. They also had me telnet to their MX
server and connected. I still don't see how it can't be them, when if I CC
someone on the same email, they receive it. We are running Exchange 5.5.

Any and all suggestions will be gladly appreciated.

 

[Jeff Stephenson [MSFT]]

What sort of server is at the other end? SMTP? If so, your Exchange
server logs should be able to tell you what is happening when it tries to
send to their server.