Why not simply turn off the notification?
As soon as I read GTD and was setting up my office The first thing I did was turn off the email notification "beep" or "blip". It's made all the difference.
I have now gotten myself into the habit of never leaving my inbox on my screen. If I'm not working on another program I either have my calendar, my CRM homepage or nothing at all on my screen.
It doesn't matter how often the email is sent or recieved it's still up to me to determine when I want to process it.