Hi,
By default email is sent using ASCII encoding, so non-ascii characters get displayed as ?.
You can change the encoding but it may or may not work with your smtp server.
<!-- leave this blank for ascii encoding -->
<add key="SmtpPreferredEncoding" value="" />
<!-- example for Russian encoding
<add key="SmtpPreferredEncoding" value="koi8-r" />
-->
Note also, that even if the asian characters are encoded correctly, if the corresponding language is not inastalled on the user's machine then the user will also see ? for any characters it does not recognize. So you my send that same message to some users and it displays correctly but for others it does not.
Hope it helps,
Joe