Disclaimer: This story is based on Unfinished Tales and the Silmarillion, both by JRR Tolkien. I am making no money from writing this, but am writing for the enjoyment of myself and others.
Letter One: Second Age 1601
Ereinion Gilgalad son of Orodreth to Tar Telperien of the line of Earendil, greeting: the Valar keep you and may no shadow fall upon the Isle of Kings.
There is much to tell you of events these past thirty years, and I regret to say that little of it is good. The mysterious shadow in the east has reappeared. We have discovered that this shadow is none other than Sauron, Morgoth's former lieutenant. We have reason to believe he may soon attack Eregion. He spent many years there without our knowledge, under the fair-guise of Annatar. The people of Ost-in-Edhil knew nothing of his true identity and the lord of that realm, Celebrimbor, informed me as soon as he discovered who Annatar truly was. By that time, Sauron was long gone from Ost-in-Edhil and could not be apprehended.
I always mistrusted Annatar. I never allowed him into my realm of Lindon, for which I am now deeply grateful, but neither I nor anyone else had dreamed that he was Sauron. We are currently attempting to discover more of his doings and whereabouts, but it seems he is the shadow that has been corrupting the men of the east and south for these past several hundred years.
Be wary when your mariners come to Middle-earth; he is sly indeed and he may well seek to suborn them to his own service. He is capable of assuming a fair form and can seem both wise and charming when he wishes. While among us he took a form similar to that of a Noldo elf, but the shadow of the east typically appeared in the form of a mortal man. He has also been known to take the form of a large owl. He can shift his form at will.
While the elves and men dwelling in Middle-earth are the people most immediately endangered by Sauron's reappearance, I doubt not that he will come looking for you once he finishes with us. He has a great deal of support among the men of the east who have turned to evil.
Therefore, I suggest that this might be a good time for some of your folk to come east to help us root out this menace before it gets any more firmly established. The situation is already bad but Cirdan, Elrond, Celebrimbor and I all fear that it may be about to get much worse.
Apart from Sauron's reappearance, everything is well with us. I hope that all is well with you, and with your people.
Manwe keep you under the One, and send fair wind to your sails.
Tar Telperien of the Line of Earendil to Ereinion Gilgalad, High King of the Noldor and King of Lindon, greetings. The Valar keep you and Middle-earth safe from the shadow.
It is with great displeasure that I read your missive describing the rise of Sauron. How did the eldar fail to notice that you had him living in one of your main cities for hundreds of years? If you personally saw enough wrong with him to ban him from Lindon, why did you not also ban him from Ost-in-Edhil? Has Celebrimbor become so powerful that he can ignore your authority without consequences? Your inability to control the House of Feanor is not my, or my people's, responsibility.
If Sauron has made himself known, I suggest you build up your forces to resist him. If you fear for the men of Middle-earth, give them weapons and train them as well.
It is not my belief that Numenor should play a military role in Middle-earth's affairs, beyond that necessary to safeguard current Numenorean possessions. I thank you for your warning, and will make certain that my mariners take precautions to avoid accidentally aiding Sauron. If they should come across any relevant information on him, I will make certain you receive it.
Manwe keep you under the one, and may your ships never founder.