Lifecycle
Subscription, unsubscribe, complaints, retries, and expiry.
Required
One-click list unsubscribe
Bulk subscription mail needs authenticated one-click unsubscribe headers that complete without login, redirects, confirmation pages, or extra choices.
RequiredDelivery status and bounce handling
Classify SMTP and delivery-status failures, stop permanent retries, back off temporary failures, and connect outcomes to the correct recipient.
RequiredRetry strategy and message expiry
Retry transient SMTP failures with backoff, cap queue lifetime, and expire time-sensitive messages before delayed delivery becomes harmful.