Thank you all for your replies. I just modified net/liftweb/util/Mailer.scala, replaced all "text/html" with "text/html;charset=UTF-8" , then problem solved.
the result mail's Content-Type part becomes: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable and "你好" is shown correctly. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Lift" group. To post to this group, send email to liftweb@googlegroups.com To unsubscribe from this group, send email to liftweb+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/liftweb?hl=en -~----------~----~----~----~------~----~------~--~---
