Looking for some advice on the most appropriate route to take for Exchange co-existence with 2007 and 2010.
We currently have a single office, with Exchange 2007 on a single server, 3 x roles - CAS, HT and MBx
Server is in Office A, the only office at the moment.
Upgrade to Exchange 2010 is planned for this server, but not for a while (months rather then weeks)
Whilst we have enabled OWA and it is accessable from the Internet in Office A, it is not widely used, the vast majority of users VPN into the office to access mail.
We now need to open another officeOffice B, and deploy Exchange. The office when open will have OWA published for users so this will also be an internet facing office.
Office A and B are both in the same AD Forest\Domain and different AD sites
The challenge is:
Looking to deploy Exchange 2010 into Office B as it fits with the bigger upgrade picture, however unsure as to co-existence and therefore deployment aproach:
Looking through the documentation there seems to be two approaches that could/would work:
1 - Deploy a CAS 2010 into Office A, setup the URLredirection with SAN certificate etc, CAS Server will proxy\redirect to Exchange 2007 CAS in local office, and also to Office B Internet connection (Assuming all dependancies are met, ie Legacy URL, SAN certificate multiple IP Addresses externally etc etc etc)
or
2 - Deploy Exchange 2010 into Office B, remove OWA access from Office A (As it is not really used) and publish OWA from office B. As Office A is no longer internet facing, Exchange 2007 can remain as is with no requirement for URL redirection etc and will happily co-exist. If users from office A need to access their mail, they can do with via Office B, as long as they use /exchange not /OwA on the URL (I think)
So finally to the question, which approach would enable deployment of Exchange 2010 with minimal initial re-configuration of 2007. I am pretty certain the second option would work, but clarification would be apreciated.
Hope the above makes sense?
Thanks in advance