How to specify the charset of outgoing messages?

[zrr]

Hi all

   The default language environment of my Emacs is 'Chinese-GBK', so
   when i post message to some chinese news group, my message is
   encoded by 'GBK' character set. The message header has this line:

           Content-Type: text/plain; charset=gbk

   But for some compatibility issues, I want encoded my message with
   'chinese-gb2312' charset. So that the people whose mail client
   doesn't support 'GBK' charset can read my articles. It seems that
   the Gnus encode the message depending on the
   'current-language-environment' varible.

   I have managed to use following settings:

   (add-hook 'message-mode-hook
          (lambda ()
            (outline-minor-mode t)
            (auto-fill-mode t)
            (set-language-environment 'chinese-gb)
            (setq locale-coding-system 'cn-gb-2312)))


   (add-hook 'message-sent-hook
          (lambda ()
            (set-language-environment 'chinese-gbk)
            (setq locale-coding-system 'chinese-gbk)))              
   
   It can works, but I think it's a expedient because switching
   language environment brings remarkable overhead. 

   Does Gnus provide a formal way to specify outgoing message
   character set?

   Thanks for any advices.

Best Regards!

Tang