Howdy! We have a two 2003-domains, with useraccounts in domain A and linked mailboxes in domain B. Domain B runs Exchange 2007 sp2 ru2. When I add rights to mailboxes in domain B, I'm able to use the following PowerShell command to add a trusted domain A user: add-mailboxpermission "mailbox_X" -user "domainA\user_Y" -accessrights fullaccess When I add send as (AD)permissions to a mailbox in domain B, I'm also able to use PowerShell to add a trusted user: add-ADPermission "mailbox_X" -user "domainA\user_Y" -Extendedrights "Send As" Now when I try to add a "manager" to a distribution group (ManageBy) who resides in domain A with the following command: set-distributiongroup -identity "Distributiongroup_X" -ManagedBy "domainA\user_Y" I get the following message: Object "domainA\user_Y" could not be found. Please make sure that it was spelled correctly or specify a different object. Am I doing something wrong here? Why isn't the trusted user accessible when adding it as a manager of a distribution group? By the way, the same error occurs when I try to add -grantsendonbehalfto. What's the difference? Is there a way to enforce the application of rights to domainA-users?

Found it! Add-ADPermission -Identity <distributiongroup_X> -User <domainA\user_Y> -AccessRights WriteProperty -Properties "Member"