parcel post

noun

(in the U.S. Postal Service) nonpreferential mail consisting of packages and parcels, weighing one pound or more sent at fourth-class rates.Compare fourth class.
the branch of a postal service that processes and delivers parcels.
the service this branch renders.

Origin of parcel post

First recorded in 1855–60

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Besides, I can send back everything in the morning, anonymously, by parcel-post.
Nobody
Louis Joseph Vance
I will let you have the helmet back by parcel-post at the earliest opportunity.
The Girl on the Boat
Pelham Grenville Wodehouse
There is a parcel-post as well as a letter penny-post in Paris.
A Trip to Paris in July and August 1792
Richard Twiss
A few thousand men by parcel-post, and some red seals-British officers.
The Weavers, Complete
Gilbert Parker
There was also a parcel that had just come by the Paris parcel-post.
813
Maurice Leblanc