Thank you for your assistantance!
There are some hardware errors in our mail server which installed the zimbra 4.0. So we have to re-install the zimbra mail server in a new machine. Now we have downloaded zimbra 4.5 and installed it in the new computer.But we don't kown how to transfer the users'data (the user name ,password ,user information, email and so on ) from the zimbra 4.0 to the new computer. What I can find only is the users' email accounts in the mysql database .But there is any password in it. I am appreciated if you could tell me the detail operational steps. Thanks!