Image blocking defeats the confirmation “hits” that spammers receive whenever one of their images is viewed. Since a "view" can include the moment you click to open a spam message, selecting "Initially block all images" is your safest choice. Here's how to do it:

1. Click Options in the upper-right corner of your Mail page and select Mail Options.
2. Under Spam, click Spam Protection.
3. At the bottom of the page is the "Image Blocking" section. You'll see three choices with three radio buttons. Select (click inside) the one that sounds right to you:
• Always show images, except in Spam folder
• Show images only from my contacts and certified senders
• Initially block all images