[itimpi]

A question mark appearing in the mobi file is a symptom of the Kindle not having font/code page combination for the character. To handle this sort of characters you need to specify the code page to be used. The reader also needs to have fonts corresponding to the specified code page.

In theory the ePub file should already be specifying the code page, but it is possible that it is being handled incorrectly. You could alwys use the Calibre 'teak epub' feature to explode the epub file and peek at the html contained in it to see if that helps - often the code page is specified at the start of the html file. Unfortunately working out the correct code page can be a bit trial-and -error. You might find that it is something like utf-8 if you are lucky.