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47451047 avatar image
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Delegating a mailbox to another domain forest.

Hello. There are two forests.

How to delegate a mailbox from domain B, to domain A ? There is a two-way trust relationship between them.

office-exchange-server-administration
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ZhengqiLou-MSFT avatar image
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ZhengqiLou-MSFT answered ZhengqiLou-MSFT commented

Hi @47451047 ,

Based on my research and tests, I think the Exchange server doesn't provide the function of delegating user A mailbox to user B who is from another forest.
I tried the linked mailbox, cross-forest mail contact and so far there are no methods could working for our case. They all failed with "You don't have permission to open this mailbox".

I find one article that's about cross forest delegation using the Outlook client to sync their calendar on Exchange 2010: Exchange Server 2010 Cross Forest Delegation
And here is a similar case about Exchange Cross Forest Shared mailbox delegation, hope those could help.

Best regards,
Lou


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Could you explain in more detail what I have to do?

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Hi @47451047 ,

Actually if you wanna give a Full Access permission to user B, I think that's impossible, which means you couldn't open a domain A mailbox from domain B.

But for the shared mailbox, you could refer to the second link above.

If you want to GALSYNC, the steps are listed here: https://docs.microsoft.com/en-us/exchange/deploy-exchange-2013-in-a-cross-forest-topology-exchange-2013-help?redirectedfrom=MSDN#deploy-exchange-2013-in-a-cross-forest-topology-with-forefront-identity-manager-2010-r2-sp1

Best regards,
Lou


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I also tried to add the full access rights to the domain-b user, succeeded, but still, I can not open the domain-a mailbox with Open Another Mailbox on OWA.
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47451047 answered

Thank you. I get it, it's not possible.

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