The thesis deals with unsolicited mail known as spam. Its main goal is to present the most widely used current methods of protection against spam and their practical application to achieve the highest possible efficiency. This study aims to find the optimal combination of protection for regular electronic mailbox. In the first part is discussed the history, reasons for the emergence and expansion of mass spam. Furthermore are introduced different types of spam, which differ with their purpose and also their dangerousness. At the end of the first part are presented global statistics for the year 2009, along with estimated total annual cost devoted to fighting spam. Mentioned are the current trends and possible future development of spam. In the second part are presented in detail various widely used methods of protection which vary in principles of operation. Their common goal is reducing the number of spam messages received to the minimum. Also their advantages, disadvantages and pitfalls of their use are analyzed. At the end of the thesis is presented a practical application of those mentioned protections in a particular case. The main contribution of the work should be limitation of received spam to a minimum and reduction of the risks associated with it based on knowledge of techniques and practices used by spammers.