Prevent shutdown if external references exist
Supported on: At least Windows Server 2008 R2 or Windows 7
Registry
HKCU
software\policies\microsoft\office\16.0\outlook\options\shutdown Value name: allowshutdownwithexternalreferences
Enabled: allowshutdownwithexternalreferences = 0
Disabled: allowshutdownwithexternalreferences = 1
Description
This policy setting controls whether Outlook should ignore external references during shutdown. If you enable this policy setting, shutdown will not occur if external references exist. If you disable or do not configure this policy setting, external references will be ignored during shutdown.