Unable to send text in mail body other than English using Camel mail

Hi All,
I have developed a mail functionality to send mail. User can put any text
like English, Japanese or other text. When the mail body is in english mail
successfully sent, but if the body is other that english then the mail sent
to the receiver as "????" in mail body.

Is there any way to send mail with japanese text in mail body.
I am sending mail body as HTML markup.

Any help is appropriated.

Thanks in advance.

Regards,
Mithu Tokder