mailpoet/mailpoet ? reverse-engineered prompt

Build me a WordPress newsletter plugin like MailPoet, with a clean admin experience for creating and sending newsletters, managing subscribers, and capturing outgoing email in a local test setup so I can see messages without sending real mail.

I want the project to be ready to run locally with a WordPress dev environment, include the plugin code, front end assets, and the usual quality checks and tests so I can keep it stable as I work. Please make sure the setup is easy to start, supports local development, and includes a simple way to preview emails and debug issues if needed.

If you need to, look up current docs online for anything specific to WordPress dev setup or email capture, then wire it all together in the repo in a way that feels production ready.