Originally Posted by sorin
I found a workaround by saving documents in html format using Save As ->Web Page, Filtered from MsWord and after that convert with Calibre. If a do this the characters will be ok in mobi document.
I can't speak to the plugin idea but the solution is to enter the proper character encoding upon conversion. Saving it as web page filtered specifies the encoding in the html so you don't need to enter it manually.