Do you use the web to read the email? How about Internet Explorer, did the problem occur? In IE, you can try to change the encoding (eg change to Big5).
What is the application name to see EMail?
Is using Web Mail (e.g. yahoo mail, hotmail)?
If using Web Mail, you can change '編碼' to 'Trad. Chinese'? If it does not solve problem, it may be the email problem - not your application.