Here’s an interesting bit from some research on how often people check their email, reported in The New York Times:
Although the only thing we changed about the participants’ lives was how often they checked their email, we observed a significant reduction in stress when they checked email less frequently.
The article is worth a read, they delve into why this might be the case.
My advice is, at minimum, turn off all of your email alerts. This isn’t an option for everyone, but I think most of us will do just fine by dealing with email only a few times throughout the day.