This policy setting controls whether pictures and external content in HTML e-mail messages from untrusted senders on the local intranet are downloaded without Outlook 2007 users explictly choosing to do so.
If you enable this policy setting, Outlook will automatically download external content in all e-mail messages sent over the local intranet and users will not be able to change the setting.
If you disable or do not configure this policy setting, Outlook 2007 does not consider the local intranet a safe zone, which means that Outlook will not automatically download content from other servers in the Local Intranet zone unless the sender is included in the Safe Senders list. Recipients can choose to download external content from untrusted senders on a message-by-message basis.
Important - Recent testing of this setting determined that it did not function as expected.