I'm working on pacing emails to a more manageable, calmer schedule. I'm doing it with essentially a UI-less system which is a rather fun way to produce an app. It simply requires a user to update their email of the website that emails them too frequently with a paced.email alias. E.g.
johndoe.shopify@daily.paced.email
johndoe.stripe@weekly.paced.email
johndoe.github@monthly.paced.email
At the end of each period, a single email is sent to the real email address containing all of the messages the alias received over that timeframe.
https://www.paced.email
I'd love to hear how you'd use it.