Substack Actions
Reward entrants for subscribing to your free or paid Substack newsletter.
The Substack action shows your newsletter's signup form inside the widget. Entrants enter their email, then finish subscribing on Substack.
Custom domains work too (like https://newsletter.yourbrand.com).
Validation: Manual
Paste your Substack URL (your Substack has to be public) and add the Newsletter Name entrants will see.