Is it possible, to achieve the proposed behavior on my FreeBSD 8.2 server:
New user ssh's into my server. He supplies as 'Login:' his student index number and a new, locked account is created with random password that is sent to his index_number@university.domain mail as authentication method. After he logs in with this password, account is fully created and activated/unlocked and the user is asked/forced to change the pass for a new one.