dead mail

noun

1. undeliverable and unreturnable mail that is handled in the dead-letter office of the general post office.

Example Sentences

“A lot of their dead mail, stuff that’s nonperishable, is given away to charity,” Tye said.

From Forbes

A mail carrier, who also served in the Persian Gulf War, later saw the letter and its old postmark and saved it from the ordinary "dead mail" pile, Rowe added.

From Seattle Times

A mail carrier, who also served in the Persian Gulf War, later saw the letter and its old postmark and saved it from the ordinary "dead mail" pile, Rowe added.

From Seattle Times

At my solicitation he readily moved for a return of all the letters, newspapers, magazines, pamphlets, &c., transmitted from the United States in 1846, and which have been refused on account of the rates of postage, and are consequently lying dead in the English post-office; also for a return of the amount of postage charged upon this dead mail matter.

From Project Gutenberg