Changing charset of mail to be sent

[Remi <email@xxxxxxxxxx>]

Hi,

I'm looking for a way to change manually the charset of mail to be sent.

I write in English, French, and Japanese. So selecting the proper 
charset can often be a pain in the behind.

If the e-mail I write is just in English, I guess any encoding can be 
fine. Though, when writing in French, I need to select iso-8859-1 or 
utf-8. In Japanese, iso-2022-jp, euc-jp, or utf-8. When I write both in 
French and Japanese, I must use utf-8, or else French accents on letters 
gets confused for Japanese characters.

Personally, I'd love to use utf-8 all the time. But for some reason, 
many free Web mail services don't work well with utf-8. (For example, 
Hotmail and Yahoo. At least the Japanese version of those services.)

I tried setting $send_charset, but often it doesn't give me the charset 
I want. I checked the manual and I don't find any way to change the 
charset manually.

So, I'm wondering, does anyone know how to change the charset of an 
outgoing e-mail manually?

In advance, thank you.

Remi