microsofft exchange 5.5 user pass limit

i have microsoft exchange 5.5 on my server and i want to set it up to require the user to have at least 4 characters to there password and to lock them out after 3 unsuccessful attempts…how can i do this..i have a windows 2000 server with active directory and i cannot figure out how to do this..and also our old nt4 server was set to 3 tries and it would allow you to unlock the account from user manager but in active directory users i do not see an account lockout listed?
thanks steve