How to force Exchange 2007 to send to another mail system

You can add a forward on a mailbox to send mail to another address, but not forward all mail for every account to another system.

If you don't want the mail going into exchange, you need to hcange your MX records (or domain registration) so it points mail to the new mail server.

I use exchange 2003, but I expect the process is similar.

Once you have set up the domain with Google, you need to remove the domain from exchange recipient policies - and get this to update your users.  None of your users should then have an e-mail address for this domain.

You may also need to check your local DNS server to ensure any reference to this domain is deleted.  Also make sure that the external DNS is updated to point to google and not your server.  It could take a couple of days for the global DNS system to show the new details depending on server caching.

Hope this helps.

Just to add to JEaston's advice:

Make sure you remove the Accepted Domain for the domain you are moving. Also, make sure your users don't use the cached email address, as this does cause issues - Get them to type it in manually for a little while, or create Exchange Contacts for the moved users and have them select from the GAL.

-Ninjatek

I'll elaborate a bit more ... i tried this on a single user domain as a test. I created the Google account and switched the MX records to point to google. External mail now flows to the Google servers and routes ok to the new mail box.

I removed the account in Exchange, removed the policy, and removed it as an accepted domain. When the user in the old exchange system tries to email the address, exchange spits out an error saying "that user does not exist"

Would this be an Outlook cache problem maybe?

The problem that you almost certainly have is that of caching and replying to emails you already have.

When you send from outlook via exchange, outlook "Remembers" the actual exchange address of the recipient, NOT just their smtp address.

To get around this problem you will need to delete all locally cached contacts and all entries in the outlook quick lookup.

What you are getting is prob nothing to do with MX records.

Yes, that is normally the case...If there are not too many email addresses being moved then you can create Exchange Contacts for them. This at least makes it easier for your users as they can select them from the GAL

-Ninjatek

Here is a link to delete the Outlook Address Cache.  Please note it will delete everything in the cache, and I have not tested the article.

http://www.howtogeek.com/howto/windows/outlook-2003/clear-the-auto-complete-email-address-cache-in-outlook/

I knew it wasn't an MX problem but i feared it was Outlook. By creating local contacts, how does that fix the problem when they are on another system?  I guess I was thinking there might be a way to force Exchange to send to google mail when a specific domain is sent to.

I don't know if your companies are like mine, but to some, it would be the end of the world if I deleted the outlook cache file!

Haha, Yes, I know those users :-)

When I said create Exchange Contacts, I didn't mean in the Outlook Client. If you create Contact objects on the Exchange server, then they will be available to all your users (Outlook; OWA etc) through the Global Address List.

Let me know if you have any questions about this procedure...

-Ninjatek

No, i understood what you meant but correct me if i'm wrong .. all i'm doing by creating contact objects is assigning an email address to an object not stored on my exchange system. If someone were to email that object, would it not fail since the Outlook client is trying to access the old object?

Yes you MUST remove the local references on the OUTLOOK clients. Just creating a new contact with the same SMTP address will not work.