Direct messaging without being friends

I would like the ability to be able to message users without having to have a mutual server or being friends. This would definitely be useful in other situations, but mine is Nookazon. This is a website in which you can trade and buy various items in Animal Crossing: New Horizons. The site lacks its own messaging system, and relies on Discord, but the requirements make it a teensy bit inconvenient to contact someone. 🍻