. Teachers and lecturers alike write and receive countless e-mails per day, and this means of communication constitutes a large amount of document exchange. Homework is sent to teachers or presentations by students to the professor for review. Cyber criminals regularly attack the e-mail systems of educational facilities, as these are often high-performance and their users generate a lot of mail. Another point is that these systems depend on powerful network connections and that very often free mail server systems are used. 