It only emails them if they don’t change it from the default settings in their user profile settings, the same settings also emails if you just reply to someone. It’s annoying as hell, but easy to turn off. Here is how you do it:
Click on your profile avatar on the top right and then the gear symbol, click on email, then uncheck the box that says “Send me an email when someone quotes me, replies to my post, mentions my @username, or invites me to a topic”.
I personally unchecked all of them, and do it for all the forums I join… since they’re usually always sending emails until you update your preferences.
