I found this in the CS manual :
6.23 SMTP with DBCS support
Mail in EBCDIC DBCS Big-5, Kanji, Hangeul, Simplified Chinese, or Traditional Chinese can be sent to a remote host using SMTPNOTE, if the SMTP server is configured with the corresponding DBCS support. Refer to the z/OS Communications Server: IP Configuration Reference for more information about configuring DBCS support for the SMTP server.
Hope this helps….