How do we deal with all of our Unread messages? What did famous people do with 100's of letters per day? What is today's advice? Consider the postal service. How often does it pick-up and deliver e-mail? Once or twice-a-day is likely enough. Any more and you couldn't get any work done. The same can apply to e-mail.
Keep your e-mail off during your busy hours at work and then read it when it's not interrupting your work. If it's part of your work flow, then define certain times that you read it. Depending on your work style, consider once an hour at the half-hour, or maybe at 10-2-4. Once you get a system in place, it will be easier to manage.
Here's the full
NY Times article on the topic. You may gleam some ideas here.