Hi @Janis Gustaps ,
Welcome to our forum!
As I know, there's no such way to create a contact group which can be synced to every member's contact list. As a workaround, It's suggested that you could to create a distribution list group with the new EAC. In this way, every member in this group can choose the distribution list group in address book when they wants to send messages to this group.
For specific steps, please refer to:
1.Go to EAC, navigate to Recipients > Groups > Distribution list;
2.In the new distribution list window, fill in the information (new group name/Alias, Owners, Members, set the permission for whether owner approval is required to join the group and whether the group is open to leave)
3.Click Save;
4.when you create a new message in Outlook client, please click "To" and you will find the distribution list group you created in address book.
For more information about creating a distribution list group, please refer to: Use the new EAC to create distribution list groups.
Hope the above help!
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