Bad news for email users like us because spammers have discovered a new way how to bypass even the most advanced spam blacklist filters using an image content. Maybe you are wondering how did this image content works, instead of spamming the emails with text based content what the spammers did is they create an image with text messages as pictures, it can also be a screenshot, and combination of these two. By doing this spam filters was fooled by the images thus it does not mark the email as spam. That is a very neat idea of bypassing email blacklist filters.
The problem with our email spam blacklist filters is that they are taught to detect spam based on the content which is text and they are not capable to read the pictures of words in images, that vulnerability was discovered by the genius people. In addition to the usual annoyance, image-based spam eats a lot of resources from your server including bandwidth than receiving a regular text mail because each image attached is most probably larger than regular spam mail – that affects the business finances. One threat that image-based spam can also bring is that there is a possibility that the spammer has inserted a unique tracker which work when a recipient opens the message and let the sender know it’s a valid email address, then you will be receiving more emails in the future.
