Postal Operations Manual, Issue 9. Updates through April 30, 2019
Centralized Delivery (Preferred Mode)Door DeliveryGeneralNewly Established or Extended Door Delivery PointsBusiness AreasHardship CasesExceptionsOptionsTransient DevelopmentsDormitories or Residence HallsForwarding of MailConversion of Mode of DeliveryCentralized delivery service is the preferred mode of delivery and may be provided to call windows, horizontal locked mail receptacles, cluster box units (CBUs), wall-mounted receptacles, or mechanical conveyors (mechanical conveyors are only for high-rise and multiple-tenant buildings, and only if certain conditions are met; consult your postmaste...See more on about ps National Association of Letter Carriers AFL-CIO
Handbook M-39 - Management of Delivery Services
Carriers should not sweep distribution cases upon reporting for work. Rather, they should proceed directly from the time recording area to their cases and without delay begin casing mail which is