(SUGGESTION) Reaching out to a friend

So one of my online friends left the server we were in together. I never bothered friending them, and when I tried messaging them, i was told I couldn’t message them unless we were friends or in a mutual server. When I tried friending them, I was told only they could send friend requests. I have literally no way of reaching out to them and they have no way to know that I’m trying to, so maybe it would be nice if they could know if someone tried messaging them even if they can’t see it?