In non-English mailing lists (particularly in Russian) there is a big problem with messages, where charset parameter of Content-Type header is set incorrectly. Sometimes software is buggy, sometimes people cannot set up their software properly, sometimes web-based email clients do not implement charsets. While reading such a mail, one should manually switch encoding in MUA back and forth. Incorrectly encoded or plain 8-bit Subject field is another big problem. Such fields often get corrupted while passing e-mail gateways. This program can be used to solve this problem while used as mail filter (in MTA, procmail, or a similar program).