Answer:

rfd

Answer	Crossword Clue
RFD	Mail abbr.
RFD	Postal abbr.
RFD	"Mayberry .."

RFD	Farm mail svce.
RFD	Old postal abbr.
RFD	TV's "Mayberry ..."
RFD	USPS experiment of 1896
RFD	Outdated postal abbr.
RFD	Some carriers' letters?
RFD	Suburban svc.
RFD	Mail svc.

RFD	Rustic mail rte.
RFD	Farm-area mail rte.
RFD	Outlying mail rte.
RFD	Rustic mail svc.
RFD	Suburban mail svc.
RFD	Rural delivery svc.
RFD	Service where there isn't a nearby P.O.
RFD	Mayberry letters

RFD	Rural mail letters
RFD	Country mail svc.
RFD	Outlying mail delivery svc.
RFD	Mail svc. that may cover a general store
RFD	"Mayberry ..."
RFD	Mayberry mail serv.
RFD	Mayberry mail service
RFD	Farmland mail abbr.

RFD	Suburban P.O. designation
RFD	Country mailing initials, once
RFD	Rustic address abbr., once
RFD	Suburban mail rte.
RFD	Farmer's mailing add.
RFD	Rustic postal abbr.
RFD	Mail service in the sticks (abbr.)
RFD	Part of a rustic address

RFD	P.O. service
RFD	Country mail rte.
RFD	Mail svc. in the sticks
RFD	TV oldie, Mayberry, ...
RFD	Rural P.O. service, once