InformationThis policy setting controls whether Outlook automatically downloads external content in e-mail from senders in the Safe Senders List or Safe Recipients List.
If you enable this policy setting, Outlook automatically downloads content for e-mail from people in Safe Senders and Safe Recipients lists.
If you disable this policy setting, Outlook will not automatically download content from external servers for messages sent by people listed in users' Safe Senders Lists or Safe Recipients Lists. Recipients can choose to download external content on a message-by-message basis.
If you do not configure this policy setting, downloads are permitted when users receive e-mail from people listed in the user's Safe Senders List or Safe Recipients List. The recommended state for this setting is: Disabled.
Malicious e-mail senders can send HTML e-mail messages with embedded Web beacons, or pictures and other content from external servers that can be used to track whether specific recipients have opened a message. Viewing an e-mail message that contains a Web beacon provides confirmation that the recipient's e-mail address is valid, which leaves the recipient vulnerable to additional spam and harmful e-mail. To help protect users from Web beacons, Outlook can be configured to automatically block the display of external content in e-mail messages. However, because this configuration could block desirable content from display, Outlook can also be configured to automatically display external content in any messages sent by people who are listed in users' Safe Senders Lists or Safe Recipients Lists.
By default, Outlook automatically displays external content in e-mail messages from people listed in users' Safe Senders Lists or Safe Recipients Lists, and automatically blocks external content in other messages. If a malicious sender is accidentally added to a user's Safe Senders List or Safe Recipients List, Outlook will display external content in all e-mail messages from the malicious sender, which could include Web beacons.
SolutionTo implement the recommended configuration state, set the following Group Policy setting to Disabled.
User Configuration\Administrative Templates\Microsoft Outlook 2013\Security\Automatic Picture Download Settings\Automatically download content for e-mail from people in Safe Senders and Safe Recipients Lists
Disabling this setting means that Outlook does not automatically download external content for messages sent by people listed in users' Safe Senders Lists or Safe Recipients Lists. This configuration can cause some disruption for users who regularly receive HTML e-mail messages that contain graphics and other external content, because they will need to download content for each message individually.