Wizards can look at absolutely *anything* in the MOO database. This includes, but is not limited to, reading your mail, viewing the commands you are typing, and listening to everything that your character hears.
The arch-wizard and the sysadmin for the MOO-server host have complete access not only to the MOO database itself but to many other possibly-relevant things.
The above mentioned parties (wizards et al), while they will endeavor to be discreet about anything incidental that turns up, nevertheless reserve the right look at anything they want, if only for the sake of being able to resolve technical problems.
Despite this power, the above mentioned parties will do their best to never release anything private (marked as -r or unreadable) to outside parties, except in rare mitigating circumstances.