When I open my mailbox notification after it says I have game mail, I don't see any unread game mail there.... I have sort of ignored it for a few days, thinking it would just dissappear after a while but it hasn't
Potentially, you could clear out your mail. I do this all the time and just keep the important things. If not, I`d go through all your mail and see if any are unread, like what Elks said.