Hi Zhang!
Greetings and congratulations from Venezuela.
iRedMail seems the software I have been looking for a very long time. I really hope that my search is over and will be able to change all my email activity with iRedMail.
For the time being I successfully moved the tar file iRedMail-0.9.4.tar.bz2 into root~ which is a huge achievement for me. I will reread patiently the "Preparations: Set a fully qualified domain name (FQDN) hostname on your server" in order to make sure that everything will run smoothly.
I agree with your philosophy that people should maintain their mails and not let that responsability to google, outlook or yahoo!