How did John the Baptist or Jesus fulfill Malachi 3:3? Malachi 3:1-3

Behold, I am going to send My messenger, and he will clear the way before Me. And the Lord, whom you seek, will suddenly come to His temple; and the messenger of the covenant, in whom you delight, behold, He is coming,” says the LORD of hosts.
But who can endure the day of His coming? And who can stand when He appears? For He is like a refiner’s fire and like fullers’ soap.
He will sit as a smelter and purifier of silver, and He will purify the sons of Levi and refine them like gold and silver, so that they may present to the LORD offerings in righteousness.


Which of the two: John or Jesus, fulfilled Malachi 3:3.
How was it fulfilled?
Why does Malachi say Levi present perfect plural &quot;offerings&quot; as a result of John or Jesus' ministry?

The difficulty arises in the fact that Jesus' supposedly put an end to the need for offerings and the verse appears to be speaking of Jewish sacrifices not the sacrifice of Jesus on the cross.
Mark quotes this passage in the first two verses of his book and it is clear that the 'beginning of the gospel' is the ministry of John. Mark also quotes from Isaiah in confirmation of this. 

Thus if the 'messenger of preparation' - spoken of by Malachi - is John the Baptist, then the 'Messenger of the Covenant' (which Malachi says is the Lord himself) is evidently Jesus - God manifest in flesh.

Then the events prophesied by Malachi must be subsequent, not just to the incarnation of the Christ, but subsequent to the ministry of the 'messenger of preparation' (the messenger who precedes the Lord's ministry). 

This, therefore, places the events of purifying and offering after the ministry of John the Baptist. Ergo, the events take place during the ministry of Jesus Christ, the Messenger of the Covenant.

So the events must be the fulfillment of what the Levitical priesthood stood for - because, as the question makes clear, the coming of the Christ would end all need for simulated sacrifices on earth. 

Therefore the 'offering in righteousness' made by the sons of Levi (the generation following the Levitical priesthood) must be the offerings made, in faith and in love, by those born from above, filled with the Holy Spirit, worshipping the Father in spirit and in truth.

This is evidently a prophecy of the New Testament, a prophecy of a new birth, a prophecy of all that is fulfilled in the sufferings and death of Christ which brings in a worshipping company, offering praises and prayers, through Jesus Christ unto God, the Father.