The simplest way to log in to the interface is with the PostgreSQL account that owns the database. Setting up other users or access rights is not mandatory. But since that account has all permissions to all objects inside the database, it is meant to be used only by administrators or fully trusted persons.
To manage users and restrict the actions that they can perform based on user profiles, Manitou-Mail provides a permissions system accessible through . Basically, an administrator can create groups, tie permissions to groups, create users, and associate users to groups. The permissions are enforced by the database itself, as they're built on top of the PostgreSQL permissions systems.
Additionally, databases with the row-level security feature (PostgreSQL 9.5 or newer) can be instructed through the interface that messages tied to certain identities can be accessed only by members of certain groups. These restrictions are based on the identity field of the messages, this identity representing the mail account for databases unifying multiple mail accounts.