allowing different users to access same email

Hi,

I have the following situation: one email acount that needs to be accessed by different users.
The account is IMAP, and up until now they all use the same user/pass.
But same emails went AWOL and off course no one did it.

What i would like is to give each user a different user/pass for the same email, so this way I could see in the logs who accessed and at what time.

Ideally I would like also to give the user different access levels (ie - user A full access, user B & C read and answer rigths, but no deletion of mails).

Any ideas?
Thanks,
JF