Because.

1 Kings 21:8-13
Then Jezebel wrote letters in Ahab's name, sealed them with his seal, and sent them to the elders and nobles who lived with Naboth in his city. . . .

2 Kings 10:1-7
Now Ahab had seventy sons in Samaria. So Jehu wrote letters and sent them to Samaria to the officials of Jezreel, to the elders, and to the guardians of the sons of Ahab, saying: . . .

2 Kings 19:9, 14
Now Sennacherib had been warned about Tirhakah king of Cush: "Look, he has set out to fight against you." So again Sennacherib sent messengers to Hezekiah with the order: . . .

2 Chronicles 32:17
He also wrote letters mocking the LORD, the God of Israel, and saying against Him: "Just as the gods of the nations did not deliver their people from my hand, so the God of Hezekiah will not deliver His people from my hand."

Ezra 4:7-16
And in the days of Artaxerxes king of Persia, Bishlam, Mithredath, Tabeel, and the rest of his associates wrote a letter to Artaxerxes. It was written in Aramaic and translated for the king. The Aramaic script read as follows: . . .

Nehemiah 6:5, 17
The fifth time, Sanballat sent me this same message by his young servant, who had in his hand an unsealed letter . . .

Acts 9:2
to ask for letters to the synagogues in Damascus, so that if he found any men or women belonging to the Way, he could bring them as prisoners to Jerusalem.

Zephaniah.

Jeremiah 29:29
And Zephaniah the priest read this letter to Jeremiah the prophet.

Jeremiah 21:1, 2
This is the word that came to Jeremiah from the LORD when King Zedekiah sent to him Pashhur son of Malchijah and the priest Zephaniah son of Maaseiah, saying, . . .

Jeremiah 37:3
Yet King Zedekiah sent Jehucal son of Shelemiah and Zephaniah the priest, the son of Maaseiah, to Jeremiah the prophet with the message, "Please pray for us to the LORD our God!"

Jeremiah 52:24
The captain of the guard also took away Seraiah the chief priest, Zephaniah the priest of the second rank, and the three doorkeepers.

2 Kings 25:18-21
The captain of the guard also took away Seraiah the chief priest, Zephaniah the priest of the second rank, and the three doorkeepers. . . .