undelivered

From un- +‎ delivered.

undelivered (not comparable)

1. Not delivered.

   Most undelivered mail has the wrong address.

   • 1659, J[ohn] M[ilton], “To the Parlament of the Commonwealth of England with the Dominions therof”, in Considerations Touching the Likeliest Means to Remove Hirelings out of the Church. […], London: […] T[homas] N[ewcombe] for L[ivewell] Chapman […], →OCLC:

     [I]t is a deed of higheſt charitie to help undeceive the people, and a vvork vvorthieſt your autoritie, in all things els authors, aſſertors and novv recoverers of our libertie, to deliver us, the only people of all Proteſtants left ſtill undeliverd, from the oppreſſions of a Simonious decimating clergie; […]

• undeliverable