- Added rate limiting for outbound email sends to prevent abuse, implemented in `internal/api/mail/sendguard`.
- Introduced idempotency key support for email sending to avoid duplicate submissions.
- Enhanced attachment handling with new limits and validation in `internal/api/mail/limits`.
- Updated outbox processing to include retry logic and circuit breaker for SMTP failures.
- Improved HTML sanitization for email content to enhance security.
- Added unit tests for new features, ensuring robust functionality and error handling.
- Updated configuration options in `.env.example` for new mail settings.
- Introduced new functionality for managing email attachments and drafts in the mail API.
- Added handlers for listing, uploading, and downloading message attachments in `internal/api/mail/handlers_attachments.go`.
- Implemented draft management endpoints for creating, updating, and deleting drafts in `internal/api/mail/handlers_drafts.go`.
- Created new service methods for handling draft and attachment operations in `internal/api/mail/drafts.go` and `internal/api/mail/storage.go`.
- Added validation and error handling for draft and attachment operations.
- Included unit tests for draft and folder functionalities in `internal/api/mail/drafts_test.go` and `internal/api/mail/folders_test.go`.
- Updated API routes to support new draft and attachment features, enhancing overall mail management capabilities.
