Policy
Block Trusted Zones
This policy setting controls whether pictures from sites in the Trusted Sites security zone are automatically downloaded in Outlook e-mail messages and other items. If you enable this policy setting, Outlook does not automatically download content from Web sites in the Trusted sites zone in Internet Explorer. Recipients can choose to download external content on a message-by-message basis. If you disable or do not configure this policy setting, Outlook automatically downloads content from Web sites in the Trusted sites zone in Internet Explorer.
d57b931e9cc0 L_BlockTrustedZones Registry
Copy registry mappings
HKCU\software\policies\microsoft\office\16.0\outlook\options\mail\trustedzone (enabled) = 0
HKCU\software\policies\microsoft\office\16.0\outlook\options\mail\trustedzone (disabled) = 1Policy notes
This policy setting controls whether pictures from sites in the Trusted Sites security zone are automatically downloaded in Outlook e-mail messages and other items. If you enable this policy setting, Outlook does not automatically download content from Web sites in the Trusted sites zone in Internet Explorer. Recipients can choose to download external content on a message-by-message basis. If you disable or do not configure this policy setting, Outlook automatically downloads content from Web sites in the Trusted sites zone in Internet Explorer.