Since the first message in 1971 email has become an increasingly popular method of communication. Still yearly growing in volume it is therefore not likely to disappear anytime soon. Unfortunately since the first spam in 1978 the spam volume is increasing even more rapidly every year and is currently responsible for around 90% of all email traffic.
Initially spam started as simple plain text messages. Then, to start avoiding the early filters, spammers started to scramble the text. With text based filtering becoming more advances the spammers switched to images. Then to avoid OCR text recognition they started to layer the images and cut it in several pieces. More recently we have seen PDF spam, Word spam and spammers keep improving their technologies (since the anti-spam community does the same).
Many security companies have predicted such new types of spam messages to start flooding the email boxes in 2008. These include MP3/audio and video spam messages. When looking back at 2007 however, PDF spam was expected to become the new standard. Against expectations, PDF spam disappeared quickly because it was too resource intensive for the spammers to send, and too time-consuming for the recipient to open. Although the first audio and video spam messages have been seen in the wild already, SpamExperts Corporation does not expect them to become a major thread anytime soon. Using advanced technologies they are fairly easy to intercept and therefore spammers will more likely remain using plain-text and images as their main communication tool.
Since the spam filters are increasingly getting better, and many companies switch to commercial antispam solutions, spammers will have to send out even larger volumes of messages to reach the critical amount of responding consumers necessary for a profit.
