I think it was around April 2011 when I completely switched off push notifications for email.
Life has been much peaceful since then. I strongly believe that push notifications of any kind are super counter-productive. All they do is make you feel important and nudge you every now and then. Plus, most of the stuff is not important and can wait. Checking constant email is not the same as doing work.
Recently I have come to love Apple’s VIP feature for the native Mail App on iOS. I now can control who I want to hear from. I can even exercise the Do Not Disturb mode post 11pm and when I need to concentrate on some tasks. The VIP feature is the ideal middle-ground to having some push notifications rather than non at all. In fact, VIP push has been most useful to me while we are building Brightpod. I find myself answering emails about product updates, bug fixes, UI changes at a much faster rate than before. Developers have questions at 2pm and instead of waiting for a few hours (until I check all my mail) I would reply to them almost immediately. It helps maintain a speedy feedback loop. If I need to focus on something, I either tuck my iPhone away in a drawer (silent mode) or enable Do Not Disturb.