When a report mailer is setup and activated, it actually logs in as the user and send the report. However this implies that this login through the backend influences the login and usage statistics of the user, by indicating that the user actually logged in, whilst s/he has not. This therefore renders the last login and usage reports useless as it is not a true reflection of the users engagement into the system.
Please omit the login of the backend as a login by the user in the login or user reports.