You only need to have the views ($Users), ($PeopleGroupsFlat), and ($PeopleGroupsHier) in your database. You also need the ($NamesFieldLookup) view if you want people to be able to begin typing the name in the To: field and have Notes find it automatically in the address books and fill in the rest.
In the person form, you must include the following fields:
FirstName (Type: Text) LastName (Type: Text) FullName (Type: Names) MailAdress (Type: Text) Type (Type: Text) with default value "Person"