Exchange 2010 Can't Users Still on Legacy Exchange 2007 Server


I am in the process of installing a new Exchange 2010 server with CAS/HUB/MB roles installed on it. This server is published behind a Forefront TMG server. The old server which is an Exchange2007 server with CAS/HUB/MB which is just behind an ASA at the moment and not published to the TMG.

When I switch everything on my router to point all incoming traffic to the TMG server I can get OWA to come up and login to a new account that I created on the Exchange box, If I attempt to access an account still loaded on the Exchange 2007 box I receive the following error "a server configuration change is temporarily preventing access to your account. Please close all internet explorer windows and try again in a few minutes. if the problem continues, contact your helpdesk."

After doing some research is the only way to fix this by changing the external URL that the old legacy server is using to say from to something new like Could I publish anything on my TMG server to get this to work without changing the external URL?

Thanks for your time and suggestions.
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sinister_krisConnect With a Mentor Commented:
If the connectors are there and the exchange boxes can contact each other, do you see anything in event log?
The external URL stays the same.

Your internal URL for 2007 changes to (users will not be impacted, outlook will autodetect)
Your Exchange 2010 will be your
Publish Exchange via TMG through to hit your Exchange 2010 CAS.

Did you create a bi-directional routing group connector?
BAYCCSAuthor Commented:
Wouldn't I just use the default connectors created with the edge subscription or do I actually have to make a b-directional connector?
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AkhaterConnect With a Mentor Commented:
legacyurl has nothing to do here it is only for exchange 2003

here is an article i wrote that should help and save me a lot of rewriting...

if you need more help plz update the thread
BAYCCSAuthor Commented:
I just looked at your article, very informative. The only question that I have is the article tells you to make both servers Internet facing I am assuming that I would basically publish the 07 server behind tmg with a new URL which I guess since I already have a san cert with registered with it so I can just use that domain name.

Or I could just move all the users over to the new exchange 2010 in one shot to advoid this.

Thank you again.
AkhaterConnect With a Mentor Commented:
you can have them both behind TMG or keep them as they are now one behind TMG and the other behind ASA it doesn't matter the idea is that they should be reachable by different URLs.

and using the is perfectly fine my previous comment was because ppl tend to believe they have to use the Exchange2003URL (also known as legacy url) which has nothing to do with 2007.

you will just need to change the ExternalURL on your exchange 2007 to

of course moving all users in one shot is another option
BAYCCSAuthor Commented:
Akhater - Thank you for taking the time to answer my questions... You are a wealth of knowledge!

Sinister- Thank you also for helping me understand which direction to move..

Glad to be of help and thanks for the points
Ditto :) happy thanksgiving
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