This happens in the latest version.
When setting the forums to UTF8 via admin and when using Jmail4 component,
any text in the reply message that is not english and text that we might have manually changed in the language file to be non english is recieved in gibrish via email.
to solve it you must add in functions_send_mail.asp under Jmail4 section:
.EnableCharsetTranslation = False
because jmail auto-encodes the body text and if the text is already in utf8 this re-encodes it and creates a problem.
note however that this still does not solve the fromName and subject bug in jmail when using non-english charachters.