Everyone Dynamic Group with Office 365 Hybrid

Many organizations have configured a dynamic distribution group that includes all users with mailboxes. This Everyone group is used for sending out company notifications and the like. Because this group is dynamic, it's automatically updated as new mailboxes are added and removed.

When you implement hybrid mode with Office 365, the dynamic group will include on-premises mailboxes but not cloud mailboxes. This is because cloud mailboxes are a different recipient type that is not included. Cloud mailboxes are MailUser recipients (an AD user with an email address but no mailbox).

One way to fix this is to modify the dynamic distribution group to include MailUser recipients. The screenshot below has enabled Users with external e-mail addresses.

This will include users with cloud mailboxes. This is the recipient filter for the dynamic distribution group:

((((RecipientType -eq 'UserMailbox') -or (RecipientType -eq 'MailUser'))) -and (-not(Name -like 'SystemMailbox{*')) -and (-not(Name -like 'CAS_{*')) -and (-not(RecipientTypeDetailsValue -eq 'MailboxPlan')) -and (-not(RecipientTypeDetailsValue -eq 'DiscoveryMailbox')) -and (-not(RecipientTypeDetailsValue -eq 'ArbitrationMailbox')))

Note that everything after the two recipient types is added automatically when you set the filter. So, don't include that information when you set a filter. If you do, those requirements will be in there twice.

Unfortunately, the recipient type UserMailbox includes on-premises resource mailboxes and the MailUser recipient type includes cloud resource mailboxes. To exclude those from our dynamic distribution group we need to manually configure the filter. We can do this by excluding the following values for RecipientTypeDetails:

• RoomMailbox
• EquipmentMailbox
• RemoteRoomMailbox
• RemoteEquipmentMailbox

I set the following filter to achieve this:

((((RecipientType -eq 'UserMailbox') -or (RecipientType -eq 'MailUser'))) -and (-not(RecipientTypeDetailsValue -eq 'RemoteRoomMailbox')) -and (-not(RecipientTypeDetailsValue -eq 'RoomMailbox')) -and (-not(RecipientTypeDetailsValue -eq 'RemoteEquipmentMailbox')) -and (-not(RecipientTypeDetailsValue -eq 'EquipmentMailbox')))

Now, the next challenge is allowing cloud users to see this dynamic distribution group. This is an issue because Azure AD Connect does not synchronize dynamic distribution groups to Office 365. For more information about this see:

• Exchange Hybrid Mode and Dynamic Distribution Groups