Buttondown Documentation
You will likely not need to interact with your newsletter settings programmatically, but if you do, this is the endpoint for you. You can create, update, and list newsletters via the API; this is ideal for integrating with Buttondown as a headless email or newsletter provider (e.g. for a SaaS product.)
A brief description of your newsletter
Custom CSS styling for your newsletter emails
Custom CSS styling for your newsletter's web presence
URL to your newsletter's icon image
URL to your newsletter's header or branding image