I’m sure I’m late to the party on this one, but if you’re a Substack newsletter reader then you can clear up your email inbox by subscribing to newsletters via RSS instead of email. Just add /feed to your publication’s home page, e.g. whatever.substack.com/feed.

There’s then a “Disable all emails” option in the Substack settings - tho beware that this seems to unsubscribe you from everything. The feeds still work fine though.

It only works for the free newsletters you subscribe to. If you pay for access to posts then they don’t appear on the feed, so you’ll still have to receive those by email or by visiting their website.