- Added new API endpoints for sending, rescheduling, and canceling scheduled outbox messages.
- Implemented outbox processing logic to handle attachments and manage message statuses.
- Introduced a dead-letter strategy for failed outbox messages, enhancing reliability.
- Updated database schema to support new outbox statuses and dead-letter entries.
- Enhanced unit tests for outbox functionalities, ensuring robust error handling and validation.
- Improved attachment handling in the outbox processor to support inline and regular attachments.
