mail subject's problem

[David Chang]

Hi all:
I am a Chinese user in cyrus.
There are a strange problem in email Subject's display problem.

If i send a mail with Chinese words in subject field from outlook express to 
myself.When i received this mail from cyrus-imap i found,that the Subject looks 
like "XXX?XXXX" .Anybody can tell me why ? 

Imapd server is:
cyrus-imapd-2.1.12
cyrus-sasl-2.1.12

David Chang