The writing and sending of official, business, and personal letters was a widely used means of communication in ancient times.​—2Sa 11:14; 2Ki 5:5-7; 10:1, 2; 2Ch 30:1; Ezr 4:7; Isa 37:14; Jer 29:1; Ac 9:1, 2; 28:21; 2Th 2:2; Heb 13:22.

The Hebrew word seʹpher refers to anything that is written and has the various meanings “book; letter; writing; certificate; deed; written document.” The Greek word gramʹma can denote a letter of the alphabet or a written document. (2Co 3:7; Ac 28:21) The Greek term e·pi·sto·leʹ is used only with regard to a written message.​—1Co 5:9.

Confidential letters were usually sealed. (1Ki 21:8) Sanballat’s disrespectful action in sending an open letter to Nehemiah may have been intended to cause the false charges set forth therein to become public knowledge.​—Ne 6:5.

In addition to papyrus, materials employed for letter writing in ancient times included ostraca (small pieces of broken pottery or earthenware) and clay tablets. Thousands of clay tablets have been found in Babylonia and other regions. Washed and cleaned, smooth clay was made into a tablet and, while still wet, it was imprinted by means of a stylus forming wedge-shaped (cuneiform) characters. These tablets were often enclosed in clay envelopes. In the case of contracts, the text was sometimes repeated on the envelope. The envelopes were sealed and then baked in a kiln or dried in the sun to make them hard and durable.​—See ARCHAEOLOGY.

Letter writing was often done by professional scribes. As in the Persian court, such scribes were usually on hand to take down official government correspondence. (Es 8:9; Ezr 4:8) Scribes were also to be found in the marketplaces near city gates, where they could be engaged by the populace to write letters and to record business transactions.

Letters were sometimes delivered by messengers (2Ki 19:14), runners (2Ch 30:6), or couriers (Es 3:13; 8:14). Postal service itself seems to have been restricted to official correspondence down to Roman times. So average persons had to rely on traveling acquaintances or merchants to deliver their letters.

Anciently, letters of recommendation were also used. However, the apostle Paul did not need such letters to or from the Christians at Corinth to prove that he was a minister. He had helped them to become Christians and therefore could say: “You yourselves are our letter, inscribed on our hearts and known and being read by all mankind.”​—2Co 3:1-3.

In the first century C.E., letters from Paul, James, Peter, John, Jude, and the governing body in Jerusalem contributed to the growth and the preservation of the unity and cleanness of the Christian congregation.​—Ac 15:22-31; 16:4, 5; 2Co 7:8, 9; 10:8-11.