Any user can create his or her own contact group in Outlook - that is, on the person's own email account. 

The contact group cannot be accessed by anyone else and must be maintained by yourself. 

Before creating your own personal contact group it is recommended to check if you can find an existing distribution list in outlook. Can be searched by start typing #. E.g a distribution list for a department can be searched by typing #AllEmpl + name of department. 

Contact groups in Outlook can contain external users (that is users who do not have an e-mail in the shared email and calendar system).