Self-host Rapid Inbox

Rapid Inbox is a self-hosted inbound email system built for developers and test teams who need to receive and inspect emails locally without relying on external email services. It features a C++ SMTP ingestion engine that provides durable acknowledgments, byte-level backpressure, and multi-worker MIME parsing. Messages, attachments, and metadata are stored on the local filesystem and in SQLite. The system supports managed domains and catch-all modes, public and private inboxes, verification code extraction in multiple languages, role-based access control with three admin roles, and API keys with fine-grained scopes. Deployment options include Docker Compose as the primary method and native systemd on Debian/Ubuntu as a secondary option. The admin console provides a web UI for managing domains, mailboxes, and messages, while HTTP APIs (v1 and v2) enable programmatic access. The project is in alpha (0.x) with explicit non-goals including outbound SMTP, IMAP/POP3, multi-node HA, and advanced anti-spam.