"For when you temporarily want to “pause” incoming email in Gmail."
The team at Boomerang, a Gmail browser extension, has created a "pause" button for your Gmail inbox. If you use the extension, you will now see a blue Pause button next to your inbox that, when clicked, will prevent any emails from coming in.
All you have to do to start getting emails again is un-pause it.
I can relate to incoming emails being distracting when there are important tasks to be done, but I can't imagine un-pausing my inbox and the stress I would probably feel with the reopening of the email floodgates.