How to hide group members in Azure AD

To hide group members, the HiddenGroupMembershipEnabled switch can be used.  HiddenGroupMembershipEnabled specifies whether to hide the members of the Microsoft 365 Group from users who aren’t members of the group. You don’t need to specify a value with this switch. You can’t change this setting after you create the group. If you create a group with hidden membership, you can’t edit the group later to reveal the membership to the group.

The HiddenGroupMembershipEnabled parameter is only available on the New-UnifiedGroup cmdlet. You can’t change this setting on an existing Office 365 Group group.

Should you wish to hide groups from Clients such as outlook, it can be done by;

1.  Setting HiddenFromAddressListsEnabled
   The HiddenFromAddressListsEnabled parameter specifies whether the Microsoft 365 Group appears in the global address list (GAL) and other address lists in your organization
2. Setting HiddenFromExchangeClientsEnabled 
   The HiddenFromExchangeClientsEnabled switch specifies whether the Microsoft 365 Group is hidden from Outlook clients connected to Microsoft 365.

Cmdlets: New-UnifiedGroup -HiddenGroupMembershipEnabled; Set-UnifiedGroup -HiddenFromAddressListsEnabled/HiddenFromExchangeClientsEnabled 

In Hybrid mode if you want to hide DL members you need to edit the below attribute (in AD onprem )and then run a ADsync :

For more details about UnifiedGroupIdParameters (HiddenFromAddressListsEnabled/HiddenFromExchangeClientsEnabled) :

-HiddenFromAddressListsEnabled

The HiddenFromAddressListsEnabled parameter specifies whether the Microsoft 365 Group appears in the global address list (GAL) and other address lists in your organization. Valid values are:

• $true: The Microsoft 365 Group is hidden from the GAL and other address lists. The group can still receive messages, but users can’t search for or browse to the group in Outlook or Outlook on the web. Users also can’t find the group by using the Discover option in Outlook on the web. For users that are members of the Microsoft 365 Group, the group will still appear in the navigation pane in Outlook and Outlook on the web if HiddenFromExchangeClientsEnabled property is NOT enabled.
• $false: The Microsoft 365 Group is visible in the GAL and other address lists.

-HiddenFromExchangeClientsEnabled

The HiddenFromExchangeClientsEnabled switch specifies whether the Microsoft 365 Group is hidden from Outlook clients connected to Microsoft 365.

• To enable this setting, you don’t need to specify a value with this switch. The Microsoft 365 Group is hidden from Outlook experiences. The group isn’t visible in the Outlook left-hand navigation and isn’t be visible in the global address list (GAL). The group name won’t resolve during the creation a new message in Outlook. The group can still receive messages, but users can’t search for or browse to the group in Outlook or Outlook on the web. Users also can’t find the group by using the Discover option in Outlook on the web. Additionally, the HiddenFromAddressListsEnabled property will also be set to true to prevent the group from showing in the GAL and in the Offline Address Book (OAB).
• To disable this setting, use this exact syntax: -HiddenFromExchangeClientsEnabled:$false. The Microsoft 365 Group is not hidden from Outlook experiences. The group will be visible in the GAL and other address lists. This is the default value.

In a hybrid deployment, if you need to hide group from GAL , you should :

1. ON Onprem , Set the msExchHideFromAddressLists attribute of the security group to True. To do this, follow these steps:
   1. Open Active Directory Users and Computers.
   2. Locate and then right-click the group object, select Properties, and then select the Attribute Editor tab.
   3. Locate the msExchHideFromAddressLists attribute, click Edit, and then change the value from <Not set> to True.
2. Wait for directory synchronization to occur. Or, force directory synchronization.

SHMUEL H.