There was a time when I used to receive upwards of 200 emails a day. I then picked up Inbox Zero and got to processing ~200 emails in under an hour.

The problem was that this also resulted in ~200 additional emails. More the emails that got sent out, more the emails I received. Faster the sending, faster the receiving.

The only way to get on top of email I realised then was to get out of email.

Highest order of productivity is not automation. It is elimination.