What's the best professional email app for people who receive 300+ emails per day?

I loved gmail, use keyboard shortcuts, priority inbox, lots of filters and labels. But lately it has become extremely slow to navigate since I'm getting more and more emails. Looking for an alternative.
Posted 
3 recommended
  1. 2
    21.co

    Replace your public email with an inbox that pays you.

    Kunal BhatiaDesign @ Mercury · Written
    Have you considered making people pay to email you? :) Might cut down on some emails that you might not need in the first place. I just registered and it was really easy to set up.
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  2. 1
    Airmail

    Lightning fast mail client for OS X

    Giacomo LawranceAuthor of thenerdystudent.com · Written
    Available on all iOS devices, it's great. Super powerful features for a low price.
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