Garbled email received - - Charset='gb2312'

We are running GW5.2.6 and have a company in China sending us emails. When
we receive the emails they are garbled. In the header of the email is says
Content-Type: text/plain; Charset='gb2312'. Could this be the reason that
the message is all garbled. Do I have to install this Charset or how do I
check to see if it needs to be installed. Any help would be greatly
appreciated.

Thanks,

Marty