Exchange 2010 OWA redirection between 2 CAS Servers

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I need some assistance, we have two AD sites, each site have separate OWA site. (Each site we have 2 CAS servers and 2 Hub Servers and mailbox Servers) when one site users login into Their Own Wep app site it is working fine. but i would like to simplfiy that, if any user choosing wrong site it should automatically redirect to other site Outlook web app.

like if the user entering the credentials (actually it should redirect to

How can i achive this. i know for Exchange 2003 we can do redirection. but Exchange 2010 how it could be.

anyone can assist will be great

Tom Vanopoulos

In Exchange 2010 and also 2007 if there are multiple AD sites the easiest approach would be to configure CAS to CAS proxy. Take a look at the following article.

In this type of scenario, you CAS sitting in AD 1 and you have a CAS + MBX in AD2. External users would hit CAS in AD1 and the request would be proxied to the CAS in AD2 where the mailbox resides in that site.

MCITP: Enterprise Messaging Administrator 2007/2010 | MCITP: Server Administrator | MCTS: Windows Server 2008 Applications Infrastructure, Configuring | MCP | MCDST

AndyD_ [MVP]

If both of these CAS are internet-facing and the externalURLs are populated, the end-user will be prompted with the URL of the better CAS to use. Is that not acceptable?


Hi Tom & Andy,

Thanks for the reply. As Andy mentioned here, URL is prompting of the better CAS Web app to use,
The requirement is now to redirect automatically to other CAS web app if they are using Another Site users. I am getting proper Response from both Web app to use the site name itself.

Both site internet-face. can we enable proxying between these site vice versa?

Brian Day MCITP

Both site internet-face. can we enable proxying between these site vice versa?
Only if you remove the ExternalURL value from both sides, but that will also require creating an additional OWA vDir on each CAS server and enabling WIA for Kerberos to work between the CAS. It also breaks the OWA URL feature in Backstage of Outlook 2010. It isn't a suggested configuration because cross-site RPC connections are more expensive than just redirecting the user and having them learn the proper URL to use. Microsoft Premier Field Engineer, Exchange
MCSA 2000/2003, CCNA
MCITP: Enterprise Messaging Administrator 2010
Former Microsoft MVP, Exchange Server
My posts are provided “AS IS” with no guarantees, no warranties, and they confer no rights.
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