'Letters' in the Bible

Moreover I said unto the king, If it please the king, let letters be given me to the governors beyond the River, that they may let me pass through till I come unto Judah;

Then I came to the governors beyond the River, and gave them the king's letters. Now the king had sent with me captains of the army and horsemen.

Moreover in those days the nobles of Judah sent many letters unto Tobiah, and the letters of Tobiah came unto them.

Also they spake of his good deeds before me, and reported my words to him. And Tobiah sent letters to put me in fear.