A few words more about productivity (previous are here and here) with a special focus on customers.
Most of the times, you just need to focus on 3-max 4 main tasks during your day.
Most of the times, these tasks are strongly customer oriented (your boss is still a customer).
So, framing your day might avoid minor tasks and get your business done.
If your colleagues know you’re busy(=unavailabe) on mornings, so you’ll plan meetings, noising phone call, etc on afternoons… a quite day will grow up your productivity!
Jim Donovan‘s post Prime time is sacrosanct will give you a business leaders outlook. 
