How to Configure Autodiscover Service for Cross Forest Mailbox Move

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When we move user mailboxes across Forests, there are certain tasks that we need to perform to make sure that users will be able to use the Autodiscover service after mailboxes have been moved from one forest to another. We will discuss the configuration required for Autodiscover Service for Cross Forest Moves. What is involved in Autodiscover Service configuration?

Business Scenario:
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Source Forest:
Domain: nitingupta.in
Email Address: gupnit@nitingupta.in
Destination Forest:
Domain: newforest.in
Username: gupnit@newforest.in

Objective:
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To move the user gupnit@nitingupta.in from Source Forest (nitingupta.in) to the destination Forest (newforest.in) and make sure that Autodiscover service will be able to handle this movement and be able to work for this scenario.

Solution Prerequisites:
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A trust between both the forests.
Delegated Exchange Server Administrator role
Membership in the local Administrators group for the target CAS server.

Steps involved:
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 - Move the User Mail box (gupnit@nitingupta.in)
 - Configure a mail contact account (gupnit@newforest.in) in the source forest (nitingupta.in) where the mailbox resided prior to the move.
 - Configuring the contact (gupnit@newforest.in) in Source forest (nitingupta.in), results in the user authenticating to original forest (nitingupta.in), redirection using the new e-mail address. Outlook 2007 client will try to contact Autodiscover service using the new email address (gupnit@newforest.in) against the new forest.
 - Use Exchange Management Shell command to set the mail contact (gupnit@newforest.in) in the source domain (nitingupta.in):
 - New-MailContact -ExternalEmailAddress 'SMTP:gupnit@newforest.in' -Name 'Nitin Gupta' -Alias 'gupnit' -OrganizationalUnit 'nitingupta.in/Users' -FirstName 'Nitin' ' -LastName 'gupnit'
 - After configuration of contact profile in Outlook 2007, when the user connects to nitingupta.in and uses the nitingupta.in credentials, Outlook 2007 client receives a redirect response from nitingupta.in, that would look something like this

< ?xml version="1.0" encoding="utf-8"?>\r\n
< Autodiscover xmlns=" http://schemas.nitingupta.in/exchange/autodiscover/responseschema/2006"> \r\n
< Account>\r\n
< Action>redirectAddr< /Action>\r\n
< RedirectAddr>gupnit@newfor est.in\r\n
< /Account>\r\n
< /Response>< /Autodiscover>

Voila!!. The user will then be able to connect to the Autodiscover service by using this new e-mail address in the newforest.in forest.

Reference:
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Overview of the Autodiscover Service
http://technet.microsoft.com/en-us/library/bb124251.aspx

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Thanks
Nitin Gupta (gupnit)
http://www.nitingupta.in/articles
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