Garbled text when using Exchange Connector to receive email. iPhone

I am using a Japan iPhone 3GS with IOS 4.0.1. I also have my gmail account setup via the Exchange connector.
When I receive emails from some Japan domains, the text become garbled. This only happens when using the Exchange connector. The preview of the email correctly shows the Japanese characters however.
I had this problem with IOS 3.1.3 as well and I hoped that the new IOS 4.0.1 would fix the problem.
I have inquired about this issue at the Google Mobile Help Forum but never received a resolution:
http://www.google.com/support/forum/p/Google+Mobile/thread?tid=3f6cd8c18ea0a3e8&hl=en
Emails with the following header information show garbled text for Japanese characters:
Content-Type: text/plain; charset=Shift_JIS
Content-Transfer-Encoding: 8bit
Emails with this header info display correctly:
Content-Type: text/plain;charset=iso-2022-j
Content-Transfer-Encoding: 7bit
-or-
Content-Type: text/plain;charset=utf-8
Content-Transfer-Encoding: base64
-or-
Content-Type: text/html; charset=Shift_JIS
Content-Transfer-Encoding: Base64
I have tried changing the IOS4 language and the result was even worse - the preview didnt even display correctly.
Does anyone know how to fix this or is this a known bug?
3GS iOS 4 gmail, exchange