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Understand how you connect Outlook Web Access (OWA) with Exchange 2010

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To understand the different redirection scenarios, it is important to understand the mechanisms that lie behind what happens when a user authenticates with a CAS to gain access to OWA Exchange 2010:
  • The user has access to the OWA URL through the web browser.
  • The user enters credentials.
  • CAS authenticates the user and retrieves the following information through the service detection request:
  • User's mailbox version
  • Location of the user's mailbox (Active Directory site).
  • CAS collects additional information based on the information in the mailbox so that it can carry out the correct operation:
- If the mailbox is Exchange 2010 and local, CAS carries out the direct connection.
- If the mailbox is Exchange 2007 and local, CAS retrieves the ExternalURL from an Exchange 2007 CAS and redirects silently.
- If the mailbox is Exchange 2003, CAS retrieves Exchange2003URL and redirects silently.
- If the mailbox is not local, CAS retrieves the destination ExternalURL and redirects or authorizes if OWA's ExternalURL is not defined in the target Active Directory site.


We will take as an example the redirection of an Exchange 2010 SP1 , we have three types of redirection for OWA in the local product:
  • Manual redirection
  • Temporary manual redirection
  • Inherited silent redirection
We will give a brief explanation of these three types of REDIRECTION:

Manual redirection

Manual redirection enables clients to not have to act as a funnel and proxy for all traffic from a central location when there are CASs that are closer to the user's mailbox.

Temporary manual redirection

In Exchange 2010 SP1 , another type of redirection has been added for OWA, known as temporary manual redirection. There are two scenarios where temporary manual redirection comes into play:

During a data center activation SWITCHBACK event, there is a possibility that the user's web browser still has the wrong DNS entry stored in the cache and thus pointing to the CAS infrastructure in the Active Directory site that already does not host the mailbox.

As a result, the CAS will issue a manual redirect to the correct Active Directory site, but the redirect is to the same URL that the user is currently using.

The second scenario is where CAS will issue the temporary manual redirection page when it detects that the local CAS site matches the RPCCLIENTACCESSSERVER value of the mailbox database, but the database is actually mounted in a different Active Directory site, so CAS issues a temporary redirect with the CAS ExternalURL in the site that hosts the mounted database.

Inherited silent redirection

For Outlook Web Access, Exchange 2010 CAS does not support the representation of mailbox data from legacy versions of Exchange.

With this we can say that we would already understand how to connect the OWA to an Exchange 2010

Ricardo Quagliano

by (3.5m points)

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