[Zope] <dtml-sendmail> and Content-transfer-encoding

Dear All: I'm using <dtml-sendmail> to send messages of Chinese characters from Zope. From time to time I got wierd mail delivery behaviors. I was told then that mail header/message body must follow RFC-822 and RFC-2047 standard with proper encoding, if not in US-ASCII. Basically these RFCs are talking about methods of encoding for non-US-ASCII characters. My question is: How do I do this in Zope? Big thanks in advance! Chien-pin