John The Baptist was the messenger. Next question.
Wrong messenger. This is pre second coming, not pre first coming. Read the stuff between what I bolded.
These are Johns words:
"Upon you my fellow servants, in the name of Messiah I confer the priesthood of Aaron, which holds the keys of the ministering of angels, and of the gospel of repentance, and of baptism by immersion for the remission of sins; and this shall never be taken again from the earth, until the sons of Levi do offer again an offering unto the Lord in righteousness."
Now, compare that with Malachi 3:3