My mailclient is mozilla and handles far eastern charactersets (chinese, japan, corean) - which I can neither distinguish, nor read, but they look nice to me - russian spam (I'm proud to know some characters
) and the western language-encodings.
But when I'm online reading my mail, the Mailprovider shows me unreadable trash.
So if it's your job to
send mail, I guess your solution is right.
You aren't responsible for the mail-sites of yahoo and hooya and
can not force them, to display the mail the right way, because they put funny ad-frames around the mail, and if the encoding is set in the wrong way, you can't do anything about it.
In other words: The mail protocol is wrapped by the http, and if sophisticated mail-clients display your mail correct - you did your job fine.
Perhaps mail-viewer in the far east are configured to display far-eastern mails correct, and most user will use the right instruments to get their mails read.