A mail delivery system and method utilize unique delivery addresses, each for a corresponding addressee, and addressee-controlled delivery codes. Each delivery code is embedded in a message address but is distinct from the unique root delivery address for the addressee. Mail that bears an address that includes an embedded valid delivery code is delivered and optionally sorted according to the code. Mail that lacks an embedded delivery code is segregated as lacking a valid code. Addressees of the system may define any number of delivery codes and may invalidate delivery codes as desired.