I subscribed to a (reputable) Substack and immediately found myself receiving unsolicited emails and other substacks I didn’t subscribe for. I also found a shadow profile was created for me.This must stop.
I'm looking to start a similar service, can I just use a bulk mailing API like Mailgun?Is that how it works?

It is fair to say that Substack has had a dramatic week and a half or so, and I talked to their CEO Chris Best about it. The company announced a new feature called Substack Notes, which looks quite a bit like Twitter — Substack authors can post short bits of text to share links