10 Tips to Turn Down Email Volume

Unsubscribe - be ruthless, love'em or dump'em . I love unroll.me for this!
White space - aim to see white at the bottom of your list of emails
Silence - turn off email sound notifications
Calendarize - drag & drop emails to your calendar or tag the email as an event to a day
Prioritize - use colour categories to highlight and or flags to classify emails for example red for ASAP, yellow for pending, grey for reference
Segregate - set up emails strategically - one work, one personal, one for very high priority info and one for deals and subscriptions and give the appropriate focus to each one.
2 min - if you can take care of it in 2 minutes - do it
Search - save time and use it often to find emails
Rules - use rules to highlight emails you need to pay attention to or to direct emails to a folder like "news"
Appointment - set a time and a time limit to emailing
BONUS tip - avoid email first thing in a day, save that for strategic thinking or meditation