Was Sauron aware of the existence of the Three Elven Rings when he forged the One? I am wondering if Tolkien's letters or materials ever address this.
The reason this question arises is that the wearers of the Three were immediately aware of Sauron's activity and purpose when he forged the One, and were able to remove them and attempt to hide all the rings. This seems like a pretty big flaw in Sauron's plan, and it seems unlikely that someone of his skill and cunning would be unaware that the rings (of his own design) would have this feature. Unless, the Seven and Nine whose forging he supervised were weak enough or had a "one way only communication" feature. Then, if Celebrimbor went on to create the Three of his own industry after Sauron had left Eregion, it's plausible that these turned out more powerful and with fewer "handicaps" built in, allowing the Elves to get the drop on Sauron.