1 Make 2 columns on a sheet of paper. 
2 Label one column Task Was Essential to do Today. other Could have waited until Tomorrow. 
3 Each time you complete a task no matter how small, mark it down in one of the columns. (If it's a particularly large task circle or highlight the mark. Then you can easily identify tasks that required more sustained concentration vs a quick task.) Anytime you complete a task related to an email (can be a reply or an action requested of you in an email), write down the letter 'e' instead of the usual mark.The aim is to count the amount of activities, don't waste time writing any detail. 

At the end of your work day see how many tasks and emails you have in the Could have waited until Tomorrow column. Repeat this activity each day until you can eliminate large non-urgent distractions from your work day. Then continue to reduce the amount of smaller Could have waited until Tomorrow column. Work toward only making and answering phone calls and responding to emails at set times. If you complete these tasks during their allocated time slot, you can count it as a Task was Essential to do Today. 
 
The purpose of this activity is to help you identify how much time you are spending on non-essential tasks. The activity itself will make you more aware of how you are spending your time. 

Getting 'quick' activities like answering emails out of the way is a bad habit. We all have to work hard to fight the email beast.