Malachi - was the last of the Nevi'im/Old Testament prophets and his story dates back to 460-450 B.C. Not only did this ancient prophet see the Israelites returning to their old, wicked habits, but he vividly predicted a judgment to be delivered by a Messiah.
Perhaps one of the most mysterious of the Minor Prophets, Malachi's early beginnings are extremely elusive and according to the 1897 Easton's Bible Dictionary, it is possible that Malachi is not a proper name, but simply means "messenger of YHWH". However, many scholars and theologians agree the ancient seer prophesied after Haggai and Zechariah (Malachi 1:10; 3:1, 3:10) during the reign of the Persian Empire.
The editors of the 1906 Jewish Encyclopedia speculated that he delivered his prophecies about 420 BCE, after the second return of Nehemiah from Persia (Book of Nehemiah 13:6), or possibly before his return, comparing Malachi 2:8 with Nehemiah 13:15 (Malachi 2:10-16 with Nehemiah 13:23).
Other theories arise as to the elusive prophet's identity ...
"Some scholars note affinities between Zechariah 9–14 and the Book of Malachi. Zechariah 9, Zechariah 12, and Malachi 1 are all introduced as The word of Elohim. Many scholars argue that this collection originally consisted of three independent and anonymous prophecies, two of which were subsequently appended to the Book of Zechariah (as what scholars refer to as Deutero-Zechariah) with the third becoming the Book of Malachi. As a result, most scholars consider the Book of Malachi to be the work of a single author who may or may not have been identified by the title Malachi. ." (from Wikipedia.com)
"The Jews of his day ascribed the Book of Malachi, the last book of prophecy, to Ezra but if Ezra's name was originally associated with the book, it would hardly have been dropped by the collectors of the prophetic canon who lived only a century or two subsequent to Ezra's time. Certain traditions ascribe the book to Zerubbabel and Nehemiah; others, still, to Malachi, whom they designate as a Levite and a member of the "Great Synagogue." Certain modern scholars, however, on the basis of the similarity of the title (compare Malachi 1:1 to Zechariah 9:1 and Zechariah 12:1), declare it to be anonymous. Professor G.G. Cameron, suggests that the termination of the word "Malachi" is adjectival, and equivalent to the Latin angelicus, signifying "one charged with a message or mission" (a missionary). The term would thus be an official title; and the thought would not be unsuitable to one whose message closed the prophetical canon of the Old Testament." (from Wikipedia.com)
Because the name of Malachi does not occur elsewhere in the Bible, some biblical historians doubt whether "Malachi" is intended to be the personal name of the prophet. None of the other prophets or prophetic books of the Hebrew Bible, as well as the Greek Old Testament, are anonymous. Many historians find a connection between Haggai and Malachi, with Haggai being expressly designated a "messenger of Elohim" (Haggai 1:13).
Opinions also vary as to the prophet's exact date, but nearly all scholars agree that Malachi prophesied during the Persian period, and after the reconstruction and dedication of the second temple in 516 BCE (Malachi 1:10; Malachi 3:1, Malachi 3:10). The prophet speaks of the "people's governor" (Malachi 1:8), as do Haggai and Nehemiah (Haggai 1:1; Nehemiah 5:14; Nehemiah 12:26).
The social conditions portrayed appear to be those of the period of the Restoration. More specifically, Malachi probably lived and labored during the times of Ezra and Nehemiah. The abuses which Malachi mentions in his writings correspond so exactly with those which Nehemiah found on his 2nd visit to Jerusalem in 432 BCE (Nehemiah 13:7) that it seems reasonably certain that he prophesied during the time of Nehemiah or shortly after.
The debate will probably continue as to Malachi's identity, wondering was this Ezra or Nehemiah or Zechariah or an unnamed individual, yet one thing remains clear, this prophet of antiquity pointed out the polluted offerings of Israel, the corrupt priests and the infidelity of the people of that time. Malachi also informed through his dire messages that one day a great messenger would come and with him would bring the "Great Day of the Lord".
In closing, it is interesting to note, the present division of the oracles (prophets) results in a total of twelve books of "minor prophets" — a number that parallels the 12 tribes of Israel. In this respect, many believe Malachi - whether that was his name or title - was indeed an individual in his own right. The Catholic Encyclopedia asserts that "We are no doubt in presence of an abbreviation of the name Mál'akhîyah, that is Messenger of Elohim."
“Remember the Law of Moses, my servant, which I commanded him in Horeb for all Israel, With the statutes and judgments. Behold, I will send you Elijah the prophet before the coming of the great and dreadful day of the Lord." ~ Malachi 4:4-5