"You have mail" won't go away.

Basically what the subject says. I got a message. I read it. The green banner won't go away though.

Albert added the "Mark all as read" thing for that purpose, I had the same problem.

Ah that works, thanks.

I just encountered the same bug. It took two applications of "Mark all as read" to get rid of the box.

I've been encountering this too, I think it has something to do with sent mail. I never get it when I just click on a mail and browse away, but when I reply, I get issues quite often. It's also possible that it's something to do with having multiple tabs of danbooru (so called "tabooru") open.