Policy
Disallow Download Headers then Full Items
This policy setting allows you to turn off the "Download Headers and then Full Items" option. Microsoft Exchange Server 2003 or later is required. If you enable this policy setting, you will turn off the "Download Headers and then Full Items" option in the Download Preferences menu in the Send/Receive tab. If you disable or do not configure this policy setting, you will allow the "Download Headers and then Full Items" option in the Download Preferences menu in the Send/Receive tab.
991c4585e78c L_DisallowDownloadHeadersthenFullItemsFileCachedExchangeMode Registry
Copy registry mappings
HKCU\software\policies\microsoft\office\16.0\outlook\cached mode\nodrizzle (enabled) = 1
HKCU\software\policies\microsoft\office\16.0\outlook\cached mode\nodrizzle (disabled) = 0 Policy notes
This policy setting allows you to turn off the "Download Headers and then Full Items" option. Microsoft Exchange Server 2003 or later is required. If you enable this policy setting, you will turn off the "Download Headers and then Full Items" option in the Download Preferences menu in the Send/Receive tab. If you disable or do not configure this policy setting, you will allow the "Download Headers and then Full Items" option in the Download Preferences menu in the Send/Receive tab.