Last month, 18% of my non-spam email turned out to be non-essential. Most of it was social lubricant, the "thank you's", "I'll get back to you's," etc. When my inbox goes below the fold (where it lives most days), it comes at a cognitive cost. To reduce the bloat I put a footer in my email for the month of June that said:

June Experiment // Need Your Help

To reduce the number of daily emails and help me stay focused bringing BetterBack to life, please respond to this email only if you have a Very Important Email to send my way. I’ll trust your judgment. Every email I don’t receive this month will help me be and do my best, so huge thank you!

It was a success! Expanding the experiment to the whole summer now...