I often tell my recruiting clients that single-tasking is a very powerful productivity strategy. That being said, I cannot think of a single thing that is more disruptive to having this type of laser-like focus than email. If you want to be super-productive, you will need to withdraw from the sugar high of constant email checking and get control of this bad habit. Constant checking of email may be one of the biggest impediments to productivity in your day. It was for me until I decided on a schedule.
 

My recommendation would be to check email about once every 3 hours. This will take discipline and feel strange at first but the payoff will be huge if you use that extra time to make more calls. "Batching" your tasks in a few segments during the day, rather than every 20 or 30 minutes between email breaks pays big dividends in terms of increased horsepower.

Think it over: How often are you checking email each day? What is all of that sporadic activity costing you? What would your productivity look like if you only checked email every three hours? Are you willing to change this habit and create a new schedule for yourself right now?