Hi silverfox55,
The following extracts taken from '2007 Microsoft Office System Inside Out', may give you an idea of what this is. This describes 'Protection Against Web Beacons'.
"Many spammers (people who send unsolicited e-mail) use Web beacons to validate e-mail addresses. The spammers send HTML-based e-mail messages that contain links to external content on a Web site (the Web beacon), and when the recipient's e-mail client displays the remote content, the site validates the e-mail address. The spammer then knows that the address is a valid one and continues to send messages to it. Outlook 2007 blocks Web beacons, displaying a red X instead of the external image. You can selectively view blocked content on a per-message basis, or you can configure Outlook 2007 to view all content but control access to HTML content in other ways. You can also turn off Web beacon blocking, if you want, and control external HTML content in other ways." (pp659-660)
"You can rest the mouse pointer on a blocked image to view the descriptive alternate text (if any) for the image. When you preview an image in the Reading Pane for which Outlook 2007 has blocked external content, Outlook 2007 displays a message in the InfoBar, indicating that the blocking occurred. You can click the InfoBar and choose Download Pictures to view the external content. Outlook 2007 then downloads and displays the content in the Reading Pane. The same is true if you open a message; Outlook 2007 displays a warning message, telling you that the content was blocked. You can click the warning message and choose Download Pictures to download and view the content. Outlook 2007's blocking of external content for messages in this way lets you take advantage of content blocking without using the Reading Pane." (p686)
Dwarf
