In the early 1980s, while working for a senior member of the Senate Foreign Relations Committee [Joe Biden], we received letters on impressive stationery from officials of the governments of KwaZulu, Transkei and Ciskei. I don't remember what they said, and in those days before the Internet there were no easy ways to verify the identities of the writers. In checking around, however, I discovered that these were from the leaders of the Bantustans, the black tribal areas created as part of South African apartheid. No other country recognized them as independent states,and we chose not to seem to acknowledge their status by replying.
Unrecognized entities troll for international recognition by such tactics. No doubt the Russian-seized Crimea would love to get a letter or call from a U.S. Senator or even the president-elect.
The United States has a similar situation with Taiwan: we deal with them through a quasi-embassy but go to great lengths not to recognize them diplomatically. Donald Trump just violated a nearly four decade practice, one even accepted by Ronald Reagan, either out of ignorance or provocative design against China. Trump's gushing conversation with the Pakistani prime minister was another example of ignoring protocol and risking major problems with India. Embarrassing! To America!