[Users] password protection

[Michael]

Regarding Liz' reply ... once they see there is Email then thy know it can be started, somehow. So i don't want to hide the start button or so. Also, hiding away the mailbox folder as a dotfile with a boring name should suffice (and i've got more ideas here). When they ever get to the point that they learn how to use grep, then it's clearly time for new concepts. We can dicsuss these in length, although it's rather getting OT here. 
But can we perhaps start with my question, how can i protect the MUA by password ?
Unfortunately, it can't be the users' password because, in short, i want this little extra security. (I think the users password will be typed in, 'in the crowd', whenever someone wants to use the computer, and will be snatched sooner or later; but the Mail password will be used only for this specific task and that should be some quiet minutes - when the Gremlins are all gone.)