If you want to use existing Active Directory groups or contacts with Exchange 2016, you must activate them for use with email.
It is not possible to activate existing Active Directory groups and contacts via the Exchange Admin Center. However, it is easy and straightforward via the Exchange Management Shell. Here is a short HowTo:
In this case, there is an Active Directory contact that has not yet been activated by email:
Existing contacts cannot be used in the Exchange Admin Center (EAC), only new ones can be created:
In contrast to mailboxes, where existing Active Directory users can also be assigned a mailbox in the EAC, it only works via shell for contacts and groups. This command can be used for contacts:
Enable-MailContact "Hans Dampf" -ExternalEmailAddress hansdampf@domain.com
It is important to enter the external e-mail address of the contact (-ExternalEmailAddress).
With existing groups, it works with the following command:
Enable-DistributionGroup Partner
In the example above, the "Partner" email group is activated. An email address does not necessarily have to be specified here (-PrimarySmtpAddress), if an address policy applies, an email address is automatically created based on the policy.
Note: Only groups with the "Universal" group area can be email-activated. An error message appears for groups of the type "Local" or "Global":
No distinction is made here between the "Security" and "Distribution" group types.
Existing users can also be conveniently activated via the Exchange Management Shell:
Enable-Mailbox hans
The commands can also be used wonderfully in conjunction with scripts, for example for the mass import of users, groups or contacts.