Solving Email has become increasingly important and widespread method of
communication because of its time speed and cheap. It is used not only for personal
contacts but also for business. The number of email messages received per day may be
thousands for companies. The spam emails are mainly an illegal form where can reach to
thousands of users easily. This type of emails has become a serious problem.
The major problems are concerning with spam for the user is time and space
waste; also, Messages can contain things that are offensive to people and can cause
general psychological discomfort. A large amount of spam can disable unsolicited email,
and personal messages can easily be lost. So there is an urgent need to control the
growing spam flood.To resolve the problem there is a growing need for emails
classification method which may be based on content, text properties and features.
Recently spammers have adopted a new style of spam; that is the image spam
trick to make the analysis of emails body text inefficient. Image Spam is an e-mail
solicitation that uses graphical images of text to avoid text-based filtering techniques,
the ambiguity to prevent recognition by optical character recognition (OCR)tools.
In this paper, we will provide a comprehensive survey and a complete
classification of the types of spam image based e-mail, the most important tricks used,
and the prominent filtering techniques used with these types of unwanted messages.
Also, review of previous works and various problems and challenges faced, in addition,
to present the standards metrics to evaluate the performance of filtering techniques.