It's not really a problem, but it's very annoying. I'll get a new mail notification on my phone, I'll see it and delete it. Thing is, when I delete the mail app from multitasking it reappears for some strange reason. Sometimes I have to repeat that process 5-6 times in order for the new message not to pop up anymore. Thing is, it doesn't happen all the time, just every few times I get new mail.