cannot create new profile with O2016 "the name cannot be matched to a name in the address list"

Hi,

I have two users (user1/user2) and a resource mailbox (office).

Exchange 2013/Office 2016

User1/user2 should only work with the office mailbox and therefore the users where not email activated.

If I try to configure the Outlook profile in the client I got the message "The name cannot be matched to a name in the address list". When I email activate the mailbox user1, autodiscover works well for the profile user1. Also when I create a new profile office I can enter the contact details and it is fine.

Why it does not work with user2, without an email mailbox?

Thanks

Christian