Nowadays, most of us can hardly imagine living without using e-mail. Certainly, electronic mail has replaced traditional mail in many cases, becoming an efficient tool for communication and marketing. We use e-mail every day, starting from personal messages and finishing on purely business-related matters: job applications, subscriptions, reservations, transactions, promotional vouchers, invoices, on-line shopping, etc. A great number of important and confidential information flows from one inbox to another one and we can never be sure of its safety. Now, let's imagine a large company, where this number increases along with the series of promotional materials, newsletters, business offers, job enquires, clients complaints, support requests, inter-departments conversations and plain rubbish messages with no value for the company. How can we possibly manage such a mass of information and keep all the messages in order and properly secured? A smart email filter seems to be a perfect solution for this problem.