postalsys/emailengine ? reverse-engineered prompt

Build me a headless email service that lets my app connect to email accounts through one simple REST API, no matter if the provider is IMAP, Gmail, or Microsoft 365. I want to be able to add accounts with a hosted login flow, sync messages in the background, send mail on behalf of users, and get real time webhooks when new mail arrives, messages change, delivery fails, or bounces happen.

Please include a basic admin dashboard where I can see connected accounts, queue status, logs, and API docs, with light and dark mode. It should support secure admin login, like password plus two factor or passkeys if possible. I also want the usual setup for running it locally or in Docker, plus clear config for Redis and the server port. If you need to check any current details, look up the latest docs online.