since most of the popular email apps like WebIS Mail, etc. are not compatible with the japanese language, and i wouldnt want to go for the built-in inbox application (its stupid), i opted for something else...
qMail
its a really nice app - easy to use, quite stable, etc. and very customizable...
actually in
http://www.wincefan.ne.jp (one of the japanese PPC site), it is rated among the popular email applictions
and
yes!!! it is a
legit application...