MailNavigator software has been created as a symbiosis of the two systems required for operation with email and usenet news: FILTER - is a powerful system for retrieving information in the archives of the majority popular mail programs: MS Mail, MS News, MS Outlook, Outlook Express, Netscape Messenger, Eudora, Forte Agent, Pegasus Mail, The Bat, Eserv, and also in all popular bases of the Fidonet informations network. The description language of the filters includes the standard operators: OR, AND, NOT, NEAR, their synonyms, and parentheses for defining the order of operators. The search can be executed on the whole word and on a part of the word. In this program it is possible to use filters on the message content, and on some fields of the message header. There is a special filter for filtering out identical messages transmitted by different newsgroups. NAVIGATOR - is a very convenient mail and news client, containing some unique capabilities. Including: the subscription manager on newsgroups, the system of sorting the incoming messages of email and news, the wonderful address book integrated in the mail system. It is optimized for operation with the messages in dial-up connection with the internet.