Spam attacks where the text is replaced with images aimed at lightly protected email systems are growing in popularity. With the variety of anti-spam filters that analyze the message content to weed out unsolicited emails, spammers continue to increasingly adopt image spam. Businesses, organizations and everyday computer users might have noted an increase of image-based spam, text e-mails that arrive in your in-box as image files. Image spam can contain a picture of words, a screenshot, a photographic image, or a combination of these. By sending emails that contain no text, only pictures, spammers found that they can fool even the most advanced anti-spam software like SpamAssassin, G-Lock SpamCombat.



Most anti-spam programs detect text-based spam very well, but they totally fail when a spam message has no text to analyze. Thus, the rapid rise of the image spams. These spam messages often include image files that have a screen shot offering the same types of information advertised in more traditional text spam. Image spam can also include unique trackers which work when a recipient opens the message and let the sender know it's a valid email address, ripe for future mailings. Image spam is probably the best technique that spammers have today to get past the anti-spam filters. Together with the image spam that uses one attached image to deliver its message, the spammers are known to send spam that contains multiple images that act like pieces in a puzzle. The recipient's email client then reassembles the pieces in the right order and displays them as one image again. In addition to the usual annoyance, image-based spam eats up more bandwidth than regular spam because each image spam message is more than seven times larger than regular spam email - what's costing users, especially business, money.

The majority of image spam is used in stock scam messages, in which the senders encourage the victims to buy a certain stock to raise its value, then quickly turn around and sell the stock themselves to make a profit.

Nevertheless, anti-spam software and service providers are able to cut down image spam, as well as HTML-based and text spam. The organizations and individual computer users having sophisticated anti-spam filters -- those that focus on both the content and origin of the messages -- have little to worry about, other than to make sure they're on the latest version of their vendor's products and receiving regular updates. They can then analyze and create rules in their software to block it. Many anti-spam software use combinations of techniques, including keywords, blacklists (of offending spam mailers), and something called "honey pots," in which they have traps set up on the Internet to collect spam messages. There are a number of approaches to protect against image spam. In current versions of Outlook, for example, images are not automatically downloaded into messages unless the user has specified that messages from the source can be trusted. G-Lock SpamCombat allows preview all the messages in a safe mode – no pictures or tracking codes are downloaded nor executed.