Email is one of the basic and most common features that internet provides us and the term is known literally to everyone who knows what internet is. Nevertheless, the service of sending and receiving electronic communications (letters, messages etc.) is of a great importance in today's world. The service has contributed to the change of the modern humanity, and the way people interact with each other that led to the change of the whole mailing infrastructure today. As a matter of fact, more letters are now sent via email than via conventional mailing services - the 'snail-mail' (called so because of the speed of delivery of such letters to the recipient). This has led to considerable drop of mail delivery companies' profits, although it in no way means that such companies have gone bankrupt because of the modern technologies. They are still delivering greeting cards, parcels, packages, big items, as well as important documents that are supposed to be in hard copy, as well as conventional letters from those who don't have internet at home or who are simply more used to the conventional mail and are not willing to yield to the invasion of modern technologies (this category of people is represented mainly by elderly people). Despite numerous advantages that we get thanks to the electronic mailing service, there are some disadvantages as well, like obtrusive advertising of various products via email (the spam). Experts say that globally there is 5 times as much spam in the internet than there is useful information.