I am not sure if this is an original or a forgery. Two things which carry weight saying this is a fake are
1. This letter is too near to what Raj Singh of Mewar wrote
2. This letter is from an enemy of Aurangzeb and not a friend of his. The tone of the letter says Shivaji is trying to be friendly to Auranzeb even after his attempt to kill him.

To the Emperor Alamgir.

This firm well-wisher Shivaji, deeply grateful for divine favour and your kindness as clear as daylight, begs to inform your Majesty as follows:

I returned from your presence without seeking your permission. It is my misfortune. But I am ready to serve you in every possible way. May your kindness be felt by everybody. As a well-wisher I am placing some matters before you.

Recently it has come to my ears that owing to your war against me, your treasury has become empty. You have decided to meet the expenditure through the imposition of jaziya on the Hindus.

Your Majesty, Akbar, the founder of your empire ruled for fifty-two years. He had adopted the excellent policy of treating with peace and equality, Christians, Jews, Muslims, Dadupanthis, Stargazers, Malakis, Atheists, Brahmins, Jains, in fact all the communities. His aim was to ensure the welfare and protection of all. That is why he came to be known as the jagadguru. The result was that to whatever direction he turned, success and glory attended his arms. He brought most of the country under his sway.

After him, Nuruddin Jahangir, ruled for twenty-two years. He led a life full of good deeds and became immortal. Shahjahan ruled for thirty-two years. He too made his life fruitful through good deeds. That is why these rulers were successful in whatever direction they turned. During their rule a number of provinces and forts came under their sway. They have passed away, but their name endures. Their greatness is beyond description. One measure of their greatness is that Alamgir has tried to imitate them but without success. He is at a loss to understand why this should be so.

The previous rulers, had they so desired, had certainly the power to impose jazia. But they felt that all men, big and small, were the children of God, and all religions, but means to the worship of the Almighty. They never allowed the feeling of religious hatred even to touch them. The memory of their kindness and the good deeds they did, is always fresh in the world. All men great and small, praise and bless them. During their rule the people had peace, and as a result, their glory increased day by day and success attended their affairs.

But during your regime many provinces and forts have gone out of your hands. The remaining provinces and forts too will be lost to you. I will not spare any effort to ruin the provinces. Your subjects are crushed. The income from your Paraganas and Mahals is decreasing day by day. It is difficult to realize even one thousand from places the income whereof was one lakh previously. Poverty is striking the kings and princes. The plight of noblemen and mansabdars is apparent to everybody. At present your soldiers are discontented, the Moslems are in anguish and the Hindus are scorched. Men are pining for bread. They are red in face because they have been striking their mouths with their hands.

They are in such deep distress, and yet you have imposed jazia on them. How could you do this? This evil news will spread from east to west. People will say “The Emperor of Hindustan has taken a begging bowl and is out to realize jazia from Brahmins, Jains, Sadhus, Jogis, Sanyasis, Bairagis, the poor and the starving people. He takes pride in doing so. He is laying in dust the name of the Taimur dynasty. Such will be the deep feeling of the people.

Your Majesty, In the Quran, God has been described as the Rab-ul-Alameen, the Lord of the entire universe, and not as Rab-ul-Musalmin, the Lord of the Mussalmans. In fact, Islam andHindusim are both beautiful manifestations of the Divine Spirit. The call for prayers is given in the mosques, Bells ring to the Divine glory in the temples. Any one bearing fanaticism and religious hatred must be said to be acting against the commands of God. To presume to draw lines on these pictures is verily to lay blame on the Divine Artist (God).

To point out blemishes in any creation only means that you are blaming the creator. Do not do so.

To be just, jaziya cannot be justified on any grounds. It is an innovation in India. This is unjust. If you feel that on grounds of religion and justice the imposition of this tax is essential, you should first realize it from Raja Rajsingh. For, he is the leader of the Hindus. It will not then be difficult to realize it from this well-wisher.