Exchange 2003 coexistence with Exchange 2010 (Edge, OWA, Certificate, DNS considerations)

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I'm most of the way through transitioning our Exchange 2003 environment to Exchange 2010 and I have a couple of questions that I hope someone can help me with. Let me explain my current configuration first:

1 Exchange 03 server we'll call EX03 (in DMZ)

1 Exchange 10 server with CA, Hub and MB roles installed, we'll call this EX10 (not in DMZ)

1 Edge 10 server no subscription configured yet (in DMZ)

Routing connector between EX03 and EX10

1 test mailbox on EX10, moved from EX03 (mailflow is fine)

We use a wildcard ssl cert

Public DNS: 2 A records named and point to our public ip that our ASA directs to EX03. There are 2 MX records named mail and mail2. I wish I knew why there were 2.

Internal DNS: 2 cname records named and that point to the 03 mail server. 3 MX records named 'mail', 'EX03' and 'EX10'

OWA address is It uses windows authentication on EX03 and forms based on EX10.

In IIS on EX03 there are 2 host headers configured. and

Ok, so now that you have all that information, here are my questions:

Currently, when I go to and login with an account who's mailbox is on EX03, I successfully login to Outlook Web Access. When I go to and login with the test account who's mailbox is on EX10, I get 'page cannot be displayed'. But ONLY if I am outside of the network. If I'm inside the network, it does forward over to Outlook Web APP. But the url does not say it says

I would like to have a period of coexistence where users are seamlessly redirected to Outlook Web App even when visiting After the coexistence and after all the mailboxes have been moved, I would like to configure the edge server and decommission EX03.

I'm almost there but am starting to get confused by OWA, certificates, edge and potentially DNS. I read in another article about configuring a 'legacy' url, but I don't quite understand what that entails.

Does the Client access server need to be in the DMZ if it is to be " internet facing" ? I'm sure the Edge server doesn't handle OWA, Active Sync, Autodiscover, etc? Only internet email.

What is the best way for me to proceed from here to make sure the rest of the transition is smooth?

Busbar [MVP]



From inside the network, when I go to, I get prompted to login to (basic authentication on Ex03). If I log in with an Ex03 account, I get Outlook Web Access. If I login with an Ex10 account, I get the Outlook Web App form (the desired result)

From outside the network, when I go to, I get prompted to login to (basic authentication on Ex03). If I log in with an EX03 account, I get Outlook Web Access. If I login with an Ex10 account, I get " Page cannot be displayed" . (the dead url shows which is the old url.. it should be showing

My goal is to have the same behavior whether I am inside the network or out. Especially out. I'm getting closer to thinking that this is half a DNS thing and half an Ex10 url redirection thing, but I can't pinpoint what or where.

Busbar [MVP]

strange, do you have the correct internal and external URLs configured.

also one note, if you have points to the exchange 2010 why you are prompted to login to mail2?!

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