I tested the mx record and this is what I got:
220 sis.onyxarchitects.com Microsoft ESMTP MAIL Service, Version: 6.0.3790.4675 ready at Tue, 30 Nov 2010 04:57:13 -0800
Not an open relay.
0 seconds - Good on Connection time
5.507 seconds - Warning on Transaction time
OK - 220.127.116.11 resolves to mail.onyxarchitects.com
OK - Reverse DNS matches SMTP Banner
250 sis.onyxarchitects.com Hello [18.104.22.168] [47 ms]
MAIL FROM: <firstname.lastname@example.org>
250 2.1.0 email@example.com....Sender OK [250 ms]
RCPT TO: <firstname.lastname@example.org>
550 5.7.1 Unable to relay for email@example.com [5054 ms]
221 2.0.0 sis.onyxarchitects.com Service closing transmission channel [47 ms]
I tested from several locations and they all say it is working but it is not working. Mail is sitting in the queue. The exchange troubleshooting assistant is telling me there is an error of Delivery status notification code 4.3.1 I have not been able to fix it. Any help would be appreciated. 2k3 server sp2 running on win 2k3 enterp. server sp2. Was working fine until the network card went bad and I changed it.