Domain seems to be setup correctly but mail not delivering

So just to be clear. We are talking about 1 Active Directory Domain and 2 Email Domain Names configured on a single Exchange 2003 Server?  There are no other Exchange 2003 server?

Here's a quick test to see if the Exchange server is even accepting email for DomainA addresses.  Let's say DomainA=domaina.com and the administrator accounts has the a email address for DomainA i.e. administrator@domaina.com

1) Open up a CMD prompt

2) Telnet to ExchangeServerIPaddress 25: c:\>telnet 192.168.1.10 25

You should get the header response from you exchange server. Now type the following lines. Each is ended by hitting the enter key.

helo

mail from: bob@bob.com

rcpt to: administrator@domaina.com

Data

TESTESTEST

(to exit the enter field hit CTLF . CTLF - which is the Enter Button followed by a period followed by the enter button)

You should get 200 or 250 responses from your exchange server.  If you get any 500 or 550 responses you are going to have to figure out why they are being generated.

After you verify that the Exchange server accepts the mail for that domain, then you can move to figuring out where it is going.

hypercat,

I checked the domain expiration and its in 2010 so that is good.

BorisMon,

I got all 250 responses from the commands and received the TESTTESTTEST message in my inbox.  So that tell us that exchange is accepting the mail?

Are users getting NDR messages back when they try to send email to domain A addresses?  Can you test this and see what the NDR says?

Also, did you do your test internally or externally?  It seems that if domain B is receiving mail, then domain A should be also, but this could not be the case if they use different public IP addresses.  If so, you need to make sure you test this externally to confirm that your router is forwarding the mail for domain A to your internal server.

Yep the Exchange server is accepting mail for that domain name.  

I forgot to ask the two basic questions:

1) was it ever working?

2) what got changed recently? new software added, changed spelling on domain name, etc. Anything even if it seems unrelated to email.

After those questions:

Go into System manager and use the message tracking feature to see if you can find your test message.  If you don't have message tracking enabled, enable it then resend the test message.  In message tracking you want to see that the message was delivered to the local store.

If you see the message but no indication that it was delivered, then the Exchange server doesn't seem to know where to but the messages nd they are floating around the MTA waiting for something to tell them where to go.

hypercat,

I sent some test messages from an external email account a couple hours ago but haven't received any NDR messages back yet. The IP addresses for both domains are the same.  I tested both internal (works) and external (doesn't work).

BorisMon,

Yes, it was working.  I don't recall when it stopped or what might have changed.  I isn't the main domain name so it took a while to figure out it wasn't working.

I checked the message tracking log and it showed up there.