In Office 365 Dedicated, there are separate OUs for Users, Groups, and Contacts.
When you create a DDG, you should specify the recipientcontainer attribute to use the User's OU. If you create the DDG without specifying the recipientcontainer attribute, the recipientcontainer attribute will be set to the OU where the DDG is created. Generally, the OU is the Group's OU.
$DDG2 = Get-Recipient -RecipientPreviewFilter $DDG.RecipientFilter
Note This will give an impact of the number of the affected users.
Article ID: 2623206 - Last Review: Mar 17, 2016 - Revision: 1