"I’ve messed around with a ton of different content and header configurations, and anything that looks like it came from an ESP (has a list-unsubscribe header,

"I’ve messed around with a ton of different content and header configurations, and anything that looks like it came from an ESP (has a list-unsubscribe header, unsubscribe links in the content, etc…) goes to either the Promotions tab or the Updates tab." This is actually a really important UX/CX thing to keep in mind when creating newsletters or other emailed publications with actual content as the product. My Pycoder's Weekly ended up in Promotions tab. Since I don't look at it every day, my initial thought was I didn't receive it. In order to have it show up in Primary, I had to create a rule on the sender. We'll see if this actually works. Granted, Pycoder's Weekly is ad-supported, but that's what I opted in for. For others creating similar subscriptions, it's probably worthwhile to mention this gmail behavior in an FAQ or some other instructions.