Guarantees

What MailKT promises, and what remains your responsibility.

MailKT guarantees

Area	Guarantee
Reads	Survive reconnects. Scans keep their frozen snapshot and UIDVALIDITY integrity.
Downloads	Bounded by an explicit byte limit and never silently truncated.
Identity	A location or part reference never resolves to a different message or part.
Watchers	At-least-once delivery with in-collection duplicate suppression and catch-up after reconnects.
Sending	Never retried. Outcomes are explicit: ACCEPTED, FAILED or UNKNOWN.
Isolation	Closing or failing one mailbox never affects another.
Lifecycle	close() is idempotent and Closed is published exactly once.
Privacy	No addresses, content or secrets in logs, exception messages or toString().
API surface	No Jakarta Mail or Angus types in public packages, enforced by an architecture test.

Your responsibilities

Area	You provide
Token storage	Durable, encrypted, atomic TokenStore.
Pending authorizations	An AuthorizationSessionStore with atomic one-time consume, shared across instances.
Checkpoints	Persist only after your processing is durable.
Idempotency	De-duplicate side effects by account and Message-ID.
Unknown sends	Reconcile by Message-ID in the Sent folder before resending.
HTTP routes	The begin endpoint and the OAuth callback route.
Logging backend	Any SLF4J 2 implementation.