Exchange 2003 Namespace Sharing - SBS 2003 - NDR's not generated

Re-submitting this in a different zone...

 I've inherited a problem where we have 2 sites... one site with exchange 2003, and another site with an SBS 2003 server.  The SBS 2003 has been using the pop3 connector to download messages from the exchange server site... and using the small business smart connector to forward their mail thru the exchange server.

After reading up, I wanted to use SMTP connectors, share the namespace (as in Microsoft KB321721) and have the mail use the exchange server as the primary server, and anything that doesn't resolve, go thru the connector to the SBS 2003 server.  (which I haven't had to really modify)

I followed the KB, got everything to work with delivery (internal and external), but somehow I've either created a loop, or missed something, as I no longer get and NDR's when I send to a non existant e-mail address.... it just stays with in the 'messages pending for deferred delivery'

The KB says 'If exchange doesn't find any match, a non-delivery report (NDR) is generated with error code 5.4.0' but I that doesnt seem to happen (unless its a very delayed reponse).  

How do I get NDR's to be generated?

I'm a novice with exchange... so let me finish with, if there is a better way to do this with the two sites (short of connecting them and putting them in the same domain, as we can't do that now) I'm open to it.
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tntmaxConnect With a Mentor Commented:
They both need to be authoritative in their own domains. You should then do just a single SMTP connector for both for address space *, then allow them to route via DNS. As long as your MX records are set correctly, it should be fine and email should get back and forth.

You don't need to smart host, unless you're dealing with a dynamic Internet connection for the SBS server.

The default SMTP server should be fine. It's just named that. Nothing magical.

Set an MX record to the SBS server and ensure that reverse DNS is configured as well.
Are they in the same domain? Are they in the same Forest? Are they in the same Exchange org? You would just need to setup Routing Groups if they are same org but different sites. If they are two separate Windows domains, then they should just route through MX records. Can you explain more about the present setup? Are they two separate Windows domains with the same email domain? You're going to have different answers based on the setup.
newactAuthor Commented:
They are in their own domains, set up independently of each other, installed completely seperate from each other. N connection to each other (no VPN's etc). The Exchange server site was set up with the original e-mail adress as authoritive, but I have since changed it (now I.e. site1.local and site2.local)

I THINK (?) the issue is generating from the SBS server.   It has a SMALL BUSINESS SMTP connector, forwarding the mail to the other exchange server, to send ALL outgoing mail out (not just forwarding the shared namespace).  No MX records point to the site where the SBS server is.  I could delete the Small Business SMTP connector, but I believe its set up as a normal SMTP connector should be.  
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newactAuthor Commented:
I should have clarified that they were both authoritive in their own domains..
I believe I follow you, and I think I know the answer,  but If I don't ask this question, I'm sure I'll set up wrong.

For the mx records, are you referring to internal DNS, or do I need to get my MX records modified completely with My ISP (like is my SBS 2003 server).   (I'm assuming its with my ISP I should change, due to the reverse DNS )

 I was just hoping to not have change with my isp, as my connection at the SBS server location is slow and problematic, and didn't want my mail to deliver there if my mail 01 and mail 02 went down.  As a side note,  I may have to switch who is hosting my MX records to do this but it can be done to resolve the problem.

Will routing by DNS result in NDR's being created when neither site has the requested e-mail address?
Okay, so here's how it works, based on your description -

1. The MX record for BOTH domains is doing to the site with the Exchange server, correct?
2. The SBS server uses the POP connector to connect to the Exchange server and download the email.
3. The SBS server also smart hosts in sending out email to the Exchange server

My question is, how is the main Exchange server holding the email for the SBS server? Is the SBS server using the POP connector to connect to another email server? Can you confirm this aspect of the setup please?

Do you mind posting the domain names so I can run some DNS tools to get a better handle of your network setup?

You won't have to change ISPs to get an MX record setup, and you shouldn't have to change ISPs to get a simple DNS change. If it's that inflexible, then you should get your domain name registrar to be your DNS host as well (Godaddy, Network Solutions, etc), as they have decent enough control panels that make it easy to make updates. With a reverse DNS, you will need to call the ISP, as they are responsible for setting it up.

If you have a flaky Internet connection to the Exchange server, then you might want to look into a 3rd-party solution that can hold your email for you then push it to your Exchange server (hint: it's a service we offer :-D). However, email should not time out until about 2 or 3 days, depending on the senders email server configuration. So intermittent email outages should not result in dropped mail.

Just to clarify, MX record updates should be done on the authoritative DNS server - that could be your server (but not likely), but probably hosted externally.
newactAuthor Commented:
I think the misunderstanding is how I answered the domain question.  We only have 1 e-mail address that we are hosting.  So only 1 set of MX records.   I'll be happy to e-mail you the domain, but I prefer not to post it on the question site.

As of right now, user accounts are set up on the main exchange server (and the pop3 connector downloads it to the SBS server every 15 minute to basically identical accounts, (with site2.local and the main domain as primary.))  The smart connector from the SBS are set so all mail gets sent to the main exchange server, and sent out (so no reverse DNS issues, but probably the reason for the lack of NDR's when I created the smart connector).

I do know this is not the best way... hence the start of this.

DNS is hosted via ATT (or whatever incarnation they are as of now) who controls our connection to the internet, and yep, I can switch to network solutions for the DNS hosting(just have to explain to the owner but that's somewhat what I meant when I said I could do it).

I believe your solution with the DNS is the best way to go, and I should go that way.... I just want to make sure before I switch my mx records that I'm still going to get the NDR's (that I didn't get when I tried to use smart connectors to solve this) by having the mail go to both locations.
So you have two separate Active Directory domains/forests, but only 1 email domain?
Is there anyway to join them to the same domain/forest and get them in the same Exchange org? This would be your best bet going forward.
newactAuthor Commented:
I accepted this as the best route to go (with the DNS at this time) and will continue to the last suggestion, in the next few months to try ajdusting the SBS 2003 site to be be part of the same domain / org, perhaps upgrading to 2008, but most likely server 2003.
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