Grant shared mailbox access to users in another trusted forest

Chiew Sheng Liew 1 Reputation point


I am unable to grant shared mailbox access to users in another trusted forest. I've used the command "Add-MailboxPermission sharedmailboxalias -User "DomainA\UserA" -AccessRights FullAccess" but is getting the error "User or group wasn't found. Please make sure you've typed it correctly."

May I know if this is by design not to be able to grant access to users in another trusted forest?

Chiew Sheng

Exchange Server Management
Exchange Server Management
Exchange Server: A family of Microsoft client/server messaging and collaboration software.Management: The act or process of organizing, handling, directing or controlling something.
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  1. Kael Yao-MSFT 26,481 Reputation points Microsoft Vendor

    Hi Chiew,

    The error indicates the user cannot be found in the forest.

    May I ask how the detailed configuration of the trust between the two forests?
    Is it a one-way trust with incoming or outgoing or a two-way trust?

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  2. Liew Chiew Sheng 6 Reputation points

    Hi Kael,

    Many thanks for capturing the screenshot. I managed to add it using exchange Powershell. I am unable to add cross forest users using Exchange admin center as it does not have to option to choose cross forest users. Can I check with you is that the expected behaviour?

    Chiew Sheng

  3. Liew Chiew Sheng 6 Reputation points

    Hi Kael,

    Yes I have 2 separate Exchange in both forest. I have tried adding using userprincipalname but it is not working as well. Is your setup using account and resource forest?