Each member of the post office has a personal database (userxxx.db) that represents the user’s mailbox. The user database contains the following:
Message header information
Pointers to messages
Personal groups
Personal address books
Rules
When a member of another post office shares a folder with one or more members of the local post office, a “prime user” database (puxxxxx.db) is created to store the shared information. The prime user is the owner of the shared information.
Local user databases and prime user databases are stored in the ofuser folder in the post office.
Because resources are addressable just like users, resources also have user databases.