Letter of Jeremiah

The Letter of Jeremiah, also known as the Epistle of Jeremy. This is a deuterocanonical (or apocryphal) book of the Old Testament. The letter is believed to have been made by Jeremiah to the people who were to be taken prisoner into Babylon. It is included in Catholic Bibles as the last part of the Book of Baruch. It is also in Orthodox Bibles as a standalone book.
Author.
Most learned people argue that the person who started the book was not Jeremiah. Jeremiah was a Hellenistic Jew who lived in Alexandria. Whoever the starter, the work was written with a purpose: to teach the Jews not to worship the gods of the Babylonians. Instead, to worship only the Lord.
Place in religious law.
The letter (epistle) is part of the Septuagint. There is no evidence of it ever having been rule bearing in the Jewish tradition.
The earliest evidence we have of the question of its canonicity arising in Christian tradition is in the work of Origen of Alexandria, as reported by Eusebius in his Church History. Origen listed Lamentations and the Letter of Jeremiah as one unit with the Book of Jeremiah proper, among "the canonical books as the Hebrews have handed them down". 
Jerome provided the majority of the translation work for the vulgar (popular) Latin translation of the Bible, called the Vulgate Bible. In view of the fact that no Hebrew text was available, Jerome refused to consider the Epistle of Jeremiah, as the other books he called apocryphal, canonical.
Despite Jerome's reservations, the epistle is included as chapter 6 of the book of Baruch in the Old Testament of the Vulgate. The Authorized King James Version follows the same practice, while placing Baruch in the Apocrypha section. In the Ethiopian Orthodox canon, it forms part of the "Rest of Jeremiah", along with 4 Baruch (also known as the "Paraleipomena of Jeremiah").
The epistle is one of three deuterocanonical books found among the Dead Sea scrolls (the other two are Ben Sira and Tobit.) The portion of the epistle discovered at Qumran was written in Greek. This does not preclude the possibility of the text being based on a prior Hebrew or Aramaic text. However, the only text available to us has dozens of linguistic features available in Greek, but not in Hebrew, hence introductions of a Greek editor, not required for minimalist translation.