Except for Isaiah, Zechariah made more predictions about Christ than any other prophet. There are many Messianic prophecies in Zechariah. Since Christ is our High Priest now, this means He is also our king now. If He is our king now, then it means that His kingdom has already come. Malachi was God's last inspired messenger to His people until the coming of John the Baptist four hundred years later.
Nothing is known of Malachi's personal life.
He was a fearless spokesman for God who rebuked the people of Israel for their sins and hypocrisy. The conditions of God's people in the book of Malachi are the same as those in the book of Nehemiah. Chapters seven to ten of Ezra also cover the same period of time. This indicates that Malachi prophesied during the two terms that Nehemiah served as governor over the little colony of Jews who had returned from captivity. 425 B.C. The people of God had become careless in keeping God's Law.