I wonder if clicking "delete" is way too much work? Not much different from getting endless friend requests in social media. If you don't use it in such ways (Not following people nor posting anything on your page).
"Problem" of handful of emails, requests, promos etc. hitting delete is quick and easy?
I generally check all incoming mail, but just to speed things up, I no longer reply to absolutely every request. I don't check out "friend requests" usually, and most of unpersonalized label spam I may deleted without reading. It means that sometimes good things are missed. Then it can be good to put topic that I'll see is personally meant for me.
This Japanese character certainly sent several mails, I don't mind. You got way way way more annoying people around than someone trying to figure out way to get his noise heard, without really knowing what to do.