Exchange Forward all mail with unresolved reciepients

jesperity used Ask the Experts™
I am running exchange 2000 on W2k Server with active directory.  The problem I have is that when the active directory domain was setup it has the same domain name as my web domain.  So if my web domain is the name of my active directory domain would also be  (This was not a smart choice but it is a little too late to go back now)

We have two mail servers, our exchange server and a hosted mail server.  The problem comes into play when someone on the internal network attempts to send mail to someone outside the network but also has the same extension of for their email address.  So what happens is that sends and email to who works at a seperate location(not on the exchange server) but gets their email through the hosted mail server.  

The problem is does not receive the email, because they do not have a valid account exchange account and receives an unknown recipient error message.  I have attempted to set-up smtp forwards for all mail with unresolved reciepients, but when I check the queue the messages are hung and does not forward.

Is there any other way for to send mail to or does anyone have an idea why the forward fails with "The connection was dropped by the remote host."

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David WilhoitSenior Consultant, Exchange

You cannot have the same SMTP domain divided that way. It's basically 2 separate orgs, and you have 1 MX record, right?

If you perform an NSLOOKUP, which server comes back as the mail server for this domain?

I think you will end up re-doing AD or collapsing your externally hosted email server ( and moving those users internally with appropriate security.  You leaped into something without a proper design.  

Sorry, you can't have it both ways. :(


You are correct that when I do an NSLookup it comes back as the exchange mail server for this domain. But why can I not forward the unresolved mail to the external mail server and let it sort it out at this point.  

I appreciate MFay's response, however redoing the AD (I assume Active Directory) is not an option.  There are too many things tied to this domain and it would be a 100 hour project to change it which I am not willing to do at this moment.  I am just looking for a way to forward the main to another mail server when they are unresolved in exchange.  If this is not possible, why does Exchange give the option of forwarding all mail with unresolved recipients??
First you need to goto the Recipient Policy with the System Manager.

Recipients, Recipient Policies, Select you Domain Policy (Probably "Default Policy"), Goto the Properties, Goto the email addresses, select the "" SMTP address, select edit, You should see a checkbox for "This Exchange Organization is responsible for all mail delivery to this address.", uncheck this will tell Exchange to keep looking if it cannot resolve an address.

Your next task will be to setup DNS, modify the SMTP connector, or modify your virtual SMTP server to tell Exchange that it can resolve to your ISP's mail server as well as your Exchange server.


This solution appears to have solved the problem.  I did have to go to and pull article Q321721 to get the details on how to make this work, but it seems to have solved the problem.  Thanks a million!

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