MailNavigator is a mail and news client that contains some unique capabilities. It contains a system for retrieving information from the archives of most popular mail programs, including Microsoft Mail, News, Outlook, and Outlook Express; Netscape Messenger; Eudora; Forte Agent; Pegasus Mail; The Bat; Eserv; and Fidonet mail. 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 or on a part of a word.