[otrs] how to stop converting incoming messages?

Hi OTRS users, how do stop OTRS from trying to convert incoming e-mail messages from utf-8 to other character set (iso-8859-1)? I am receiving administrator notifications like this: Charset encode 'utf8' -=> 'iso-8859-1' (New Ticket [2009052610000014/Dati ar zvaigzni] created (TicketID=9,Queue=incoming,Priority=3 normal,State=new)) not supported! Charset encode 'utf8' -=> 'iso-8859-1' (Sent email to '"HELP" <***@***.com>' from 'customer <***@***.com>'. HistoryType => SendAutoReply, Subject => [Ticket#2009052610000014] Dati ar zvaigznīti;) not supported! Thanks for your time, Ivars