Malachi is Mordecai. Why is he called Malachi? Because he was second to the king (melech) and was looked upon as an angel (malach) (Maharsha). However, the Talmud concludes that Malachi is Ezra (Megillah 15a).

His name, his origin, his personality, and the pe- riod in which he wrote seem to be in dispute. Based on the three chapters that make up his book, this last of the Twelve “minor” Prophets is preaching his message to a people who have once again become established in the Promised Land. Yes, exile is over, but apparently Israel’s inclination toward evil has returned in spades.

The name of the book could well be derived from the sentence “Behold, I send My messenger” (Malachi 3:1). “My messenger” is the translation of the Hebrew malachi. And this messenger has a classic prophetic message: although it is clear that the Lord loves Jacob and rejects Esau, his favored ones must recognize their obligation to serve Him with proper behavior and respect. The priestly cult, at least in this prophet’s eyes, needs purification. In addition, the people must refrain from non-sanctioned behavior such as observing foreign gods and intermarrying.
“The messenger” is to discharge these Heavenly orders. In the name of the Lord he speaks: But who may abide the day of his coming?
And who shall stand when he appeareth?
For he is like a refiner’s fire,
And like fullers’ soap;
And he shall sit as a refiner and purifier of silver,
And he shall purify the sons of Levi,
And purge them as gold and silver;
And there shall be they that shall offer unto the Lord
Offerings in righteousness (Malachi 3:2-3).

Sanitized and purified, Judah and Jerusalem will be restored as in the days of old. More admonitions follow. The people are warned to pay their tithes wholeheartedly; failure to do so will result in exclusion from the Lord’s promise of Heavenly reward.
In consonance with Zechariah, whose visions explored the “end of days,” Malachi adduces his own version of eschatology. That turns out to be “one hot day!”
For, behold, the day cometh,
It burneth as a furnace;
And all the proud, and all that work wickedness, shall be stubble;
And the day that cometh shall set them ablaze...(Malachi 3:19)
But to the God-fearers, there is hope. At last, the identity of “My messenger” is revealed. From behind the curtain emerges the mystery guest... the messenger is Elijah!
Behold, I will send you Elijah the prophet
Before the coming
Of the great and terrible day of the Lord (Malachi 3:23).
We end the prophetic books as they had begun. Obey God and receive the “joy of victory.” Disobey Him and endure the “agony of defeat.” At this time, and in this place, we are discussing nothing less than matters of eternity.