Have you found lately that you might be working intently on something when you hear that little ding or see the number change on your email icon that lets you know there's a new message and suddenly you cannot concentrate?
According to Charles Duhigg in a NY Times article, as soon as we get a signal that we have a new message, "the brain starts anticipating the neurological “pleasure” (even if we don’t recognize it as such) that clicking on the e-mail and reading it provides. That expectation, if unsatisfied, can build until you find yourself moved to distraction by the thought of an e-mail sitting there unread — even if you know, rationally, it’s most likely not important."
You'll save yourself a great deal of time, used up in the mental distraction as well as the physical distraction of clicking away from your work and onto the email, by turning off your email when working on something important. In your day-to-day schedule planning, I strongly recommend turning on your email during specific times, turning it off for a specified length of time, then turning it back on. For example, turn on the email in the morning and deal with important items. Then turn it off for 45 minutes while you focus on other work. Take a break from that work for 15 minutes by walking around for 5 or 10 and checking your email for 5 or 10 minutes. Then repeat. You'll find yourself to be far more productive during those 45 minute stretches.
As Duhigg goes on to say, "once you remove the cue by disabling . . . the chiming of your (email), the craving is never triggered, and you’ll find, over time, that you’re able to work productively for long stretches without checking your in-box."