While I get that it feels spammy, and I passed this along, I was pretty certain and DMY confirmed that permission was granted a long time ago when we opted into something, and it was disclosed that it included substack newlstters. When they were infrequent, we didn't think about it.

After much discussion in the private slack channel for active and emeritus editors, the unsubscribe button as been found. At the very bottom of the emails, in grey, under Substack's corp address. Since many of the emails are so long, you may need to click on the unsnip link to open it up to then be able to scroll to the bottom

Correction — it’s not the corp address — it’s DMY’s copyright address