This policy setting controls whether Outlook users can expand Contact Groups when addressing e-mail messages.
If you enable this policy setting, Outlook users cannot expand Contact Groups.
If you disable or do not configure this policy setting, when Outlook users add a Contact Group to the To, CC, or BCC fields of an e-mail message or other item, they can expand the Contact Group to see the e-mail addresses of everyone in the group.
| Registry Hive | HKEY_CURRENT_USER |
| Registry Path | software\policies\microsoft\office\16.0\outlook\options\mail |
| Value Name | disabledlexpansion |
| Value Type | REG_DWORD |
| Enabled Value | 1 |
| Disabled Value | 0 |