Apple Mail cannot encoding issues (Chinese Asian Language)

I've abandon Mail for almost 2 years, 2 issues I had before is the 'disappearing mail' and the encoding problem.

Now with my new MBP 17" I decided to use Mail again. I am getting the encoding problem again.

Things I tried already:
1. set the default encoding using Terminal to "BIG5"
2. check under 'Composing' preference for 'Plain Text', uncheck 'use the same message format as the original message'
3. Tried manually setting the encoding before sending. But in few instance Apple Mail tells me that there is an Error and cannot change the encoding. Even I succeeded in changing the encoding, there is no guarantee that the other side can read it properly.

This usually happens when I 'reply' or 'forward' a Chinese email to someone. So far it happens to the HTML type email.

Still I am getting problem sending mail that Outlook can properly decode by itself. To fix this from the Oulook side, they need to open the message by double click, select encoding for the message, and pick either UTF-8 or BIG5 (if the message is BIG5, select UTF-8 and vise versa) then the message will display properly.

I know this could be an Outlook problem (probably is) but I cannot tell my customer to change encoding each time. I really need a way to do this from the Apple Mail side.

The following is just one example of HTML email I replied and turns out to be BIG-5 under Outlook, but user need to select UTF-8 to view it.

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In-Reply-To: <050201c7154d$3fa791c0$bcdd123d@SN012345678912>
References: <LKEDIGOJPAOGCDEMMOIIMEIGCCAA.ken.jia@synfort.com> <050201c7154d$3fa791c0$bcdd123d@SN012345678912>
Mime-Version: 1.0 (Apple Message framework v752.3)
X-Priority: 3
Content-Type: multipart/alternative;
boundary=Apple-Mail-1--121729776
Message-Id: <801C6B0E-7C7A-400A-8984-8BB4116EEA13@synfort.com>
Cc: =?BIG5?B?RXZhSG/EX7XY?= <eva@polar-nedlink.com>,
=?BIG5?B?SG9sbHlfUG9sYXLEX7XYs6Ks9cRS?= <marketing@polar-tannery.com>,
=?BIG5?B?U3VzYW5hU29vxF+12A==?= <annabel.ng@amlgroup.com.hk>,
=?BIG5?B?UGh5bGxpc8Rftdg=?= <phyllis@polar-nedlink.com>,
=?BIG5?B?S0VOLkpJQbjrvuWoyA==?= <ken.jia@synfort.com>,
"Viv Lee" <vivian@polar-nedlink.com>,
=?BIG5?B?SmFuZUNoZW6zr6Tlr3U=?= <jane.chen@synfort.com>,
=?BIG5?B?RWR3aW5ZYW+rwKWuxe8=?= <edwin.yao@synfort.com>,
=?BIG5?B?MDA3NDalVMBzrvw=?= <tonny.ran@synfort.com>
From: James Yao <james.yao@synfort.com>
Subject: =?BIG5?B?UmU6IMRftdizbqT7pdarfr3osN3DRA==?=
Date: Sat, 2 Dec 2006 07:42:27 +0800
To: =?BIG5?B?vki0ZqzCIEpvYW4gVGFuZw==?= <joan@polar-nedlink.com>


--Apple-Mail-1--121729776
Content-Transfer-Encoding: quoted-printable
Content-Type: text/plain;
charset=BIG5;
delsp=yes;
format=flowed

Hi xxxx...... (body of the message)
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I need help here, I still like the operation in Apple Mail but this is killing me. Please help.