Design and Evaluation of Proof of Work Based Anti-Spam Solution

According to recent reports, most of the overall email traffic consists of spam, which represents an abuse for the purpose of mass distribution of unwanted messages. Spam can lead to serious attempts at a data breach or email consumer's identity theft, also. There are a lot of different anti-spam solutions. The aim of this paper is to design and evaluate an anti-spam solution based on a novel Proof of Work concept. The proposed solution requires a certain amount of work from a sender prior to the transfer of an email message. The extended SMTP protocol will be designed in order to enable the evaluation of client credibility using the Proof of work algorithm. The design of the proposed solution will be presented in detail. The implemented system will be evaluated in distributed spam attempt, simulated by Seagull tool. An evaluation of the client work, the impact on the overall amount of sent spam messages, as well as the impact of distributed spam attempt on the attacked server resource usage will be shown. We will show that the proposed solution helps in reducing spam traffic and server load, while it doesn't diminish the consumer experience of legitimate email users.