API Directory / Communication

Email, SMS, push, and chat APIs differ, but all can accept a request without delivering a message. The communication API directory is a starting point; validate the complete lifecycle.

Delivery trial

• Send consented test messages to representative destinations and verify sender identity rules.
• Distinguish accepted, queued, delivered, bounced, failed, and unknown states.
• Test webhook signatures, duplicate events, out-of-order notifications, and retries.
• Define idempotency so a timeout does not generate two messages.
• Check unsubscribe or opt-out handling, rate limits, templates, localization, and data retention.

Never treat an HTTP success code as proof a recipient saw the message. Provide a support path for failures and honor consent rules in every channel.