(Just kidding. I've never sent them anything.)
I moved to south central rural Kentucky 13 years ago. I was shocked that some still call them “colored” in this area. And some of them that use that word are, in fact, “colored” themselves.
Fact is, the only negative word is one that is intentionally insulting, like the N-word, “spear chucker”, “jungle bunny” or other colorful colloquialisms. And “mud-shark” is a backhanded insult. Heck, we call “lowlife” white people “white trash”, and my take is the word for “lowlife black people is, in fact, the N-word. Yet nobody dings you for saying “white trash”.
The other funny thing is that none of the names anybody uses to insult white people have any affect on me at all. Words like cracker, etc. After all, why do you think they call it “Cracker barrel”? 🤣
And I suspect self respecting black people don’t care what you call them, and the word you use is a reflection of you, not them.