Custom Script

Looking for a simple script that allows me to allow people to add listings on my website only if they add an image link of their created listing on their website. It will be a simple image about 70x70 pixels with the websites logo on it. When clicked it will go to my website where they created their listing. The script will need to keep track if the logo link is still on their website, and if the logo link is taken off, their listing is removed/invisable. Its basically a reciprocal link checker. When they remove it, and the listing is removed, the script will need to send the person and email saying that their listing has been removed because they removed the logo link and will be visible again only when they add it back on.