Malicious email senders can send HTML email messages with embedded Web beacons, which are pictures and other content from external servers that can be used to track whether recipients open the messages. Viewing email messages with Web beacons in them provides confirmation that the recipient's email address is valid, which leaves the recipient vulnerable to additional spam and harmful email.
By default, Outlook does not download external content in HTML email messages from untrusted senders over the local intranet. If this configuration is changed, Outlook will display external content in all HTML email messages received via the local intranet, which could include Web beacons. |