Hi @dirkdigs ,
Based on my research and test, the address book may only display the list for your account, and there seems to be no option that could add the contacts folder for shared mailbox to address book dialog directly except you add it as a separate account in your profile.
As a workaround, in addition to creating a new address book as mentioned by michev, we could also try to create a Public Folder to save your contact items and assign the permission to users, so that we could add this contact list to address book directly via set the Folder's properties:
- create public folder and assign the permission in exchange admin center
- login to your outlook client and switch to Folder view(ctrl + 6)
- create contact folder under public folder(Right-click your public folder>New folder>folders contain "contacts item")
- add your contacts in this folder and add it to your address book(right-click the folder>properties>Outlook address book>check the option and type the name it displays)
Hope that would be helful to you.
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