'Letters' in the Bible

I also asked the king, "If it seems good to you, order that letters of authorization be given me for the Trans-Euphrates governors, so they will allow me to pass through to Judah,

The king granted this for me, according to the good hand of my God. So I went to the Trans-Euphrates governors and gave them the king's letters of authorization. The king also sent army officers and cavalry to accompany me.

Meanwhile, at that time the nobles of Judah continued to send many letters to Tobiah, and Tobiah kept sending letters to them.

Furthermore, they kept reporting Tobiah's good deeds to me, and kept repeating what I told him. Tobiah kept sending letters to intimidate me.