"Greetings from Ural, Russia!"

Do you mean, "Who we DON'T know yet?"

Hi. Do you mean a letter to a person you *don't* know yet? If so, you could introduce yourself like: "Greetings to you from ............, in Russia. My name is .........., and I ........." (then just say whatever you want to talk about). Hope this helps

Formal: Dear sir, ... . As with Angela's answer "Greetings to you from Ural, Russia." also works if you want the "to you". These work for people you know, or don't know.