In today's world of globalization and technology without borders, the emergence of the internet and the rapid development of telecommunications have made the world a global village. Recently, the email service has become immensely used, and the main means of communication because it is cheap, reliable, fast, and easy to access. In addition, it allows users with a mailbox (BAL) and email address to exchange messages (images, files, and text documents) from anywhere in the world via the internet. Unfortunately, this technology has become undeniably the original source of malicious activity, in particular the problem of unwanted emails (spam), which has increased dramatically over the past decade. According to the latest report from Radicati Group, which provides quantitative and qualitative research with details of the e-mail, security, and social networks, published in 2012, 70-80% of email traffic consists of spam. The goal of the chapter is to give a state of the art on spam and spam techniques and the disadvantages of this phenomenon.