The setting I want on most sites that send email is: "Only on Human Action".
If someone talks with me using your chat. Or if they "friend" me. Or whatever your platform does. An email is probably reasonable.
What I don't want is your automated attempts at "increasing engagement" or encouraging "daily active use." Those are all spam to me and make me want to disable all email for your domain.
When I get too much mail you want me to blame the humans, not your platform.