I need some help with exchange linked mailboxes with active directory trusts.
I have an AD-trust between two domains (Type External, bidirectional, non-transitive, selective authentication). Domain A is hosting the Exchange server (2016), Domain B has the user accounts. When I try to add a linked mailbox on the Exchange in Domain A, the wizard requires to enter admin credentials from Domain B. I read this Microsoft KB and this should not be happening: https://docs.microsoft.com/en-us/exchange/recipients/linked-mailboxes?view=exchserver-2019#use-the-eac-to-create-a-linked-mailbox
There it says:
You won't be prompted for administrator credentials if you've created a two-way trust or have created another one-way outgoing trust where the account forest trusts the Exchange forest.
What I don't understand is: When I enter a domain user from Domain B (a normal user, without admin rights!), the wizard accepts this and I can create the mailbox. I tested the login in OWA with the credentials from Domain B and it worked.
Can someone explain me, why the wizard want me to enter admin credentials from Domain B?
What if I don't enter an admin user and just use a normal user without admin rights - am I missing something? Is something not going to work?
What do I have to configure, so that I don't have to enter any credentials, like it's described in the Microsoft KB?
Thank you very much.