Remember Covey's 7 Habits lesson on Urgent vs. Important? Think about this fact from: Quick tips on processing your email inbox
Zen slap: An email auto-check set for every minute means 60 potential distractions every hour, or almost 500 per day. Look back at a week of your emails and ask yourself: how many distractions was that really worth? How much crucial, instantly actionable email did I receive to make it worth shifting my attention over 2000 times?
How about have email set to check every 6 minutes, and minimize your email client when working on projects that require concentration. If it's really important they can call you or IM you after all.