Very Computer

Sorry wrong post earlier in IIS list.
Exchange 5.5, large student info store, daily backups,
backup account shows as latest user each day on accounts
until a user accesses their email box, trying to
determine who has not used their email yet and who has.
I am looking for a utility (or logging) that gives me
this type mail box usage data in a certain time period.
If anyone has seen or used a utility like this please let
me know. Thanks