There is a plugin that you have to have if you are using Mozilla Thunderbird as your email client. It’s called the Adblock Plus which enables you to right click and image, select the “adblock plus” option and that image or ad will forever be blocked from their on. It’s a fantastic tool to have to prevent spam images from even being downloaded onto your computer. I highly recommend this plugin for you Thunderbird images. I have set it up and it is working great for me. And if by chance you are not using Thunderbird and you are still using Outlook, switch! You will be happy when you do.