http://www.mustbegeek.com/create-distribution-group-in-exchange-2016/

Distribution groups are used to send email.  Security groups, which we have used in AD, can be converted to distribution groups.  You will need some additional users to do this.  You might also try adding your mail-enabled contacts to a group.  Note - the article also uses an OU, if you don't specify an OU it puts the group into the USERS container (which is not an OU remember).