Welcome, verification, and password-reset messages with safe retries.
“Use one idempotency key per product action so a retried request cannot send twice.”
SAFEretries
// 02 / ARCHIVE
Receipts and fulfillment updates built from versioned templates.
“Send individual receipts or a batch while suppressions and project quotas remain enforced.”
100batch limit
Auditable delivery state for security-sensitive notifications.
“Treat provider status and signed webhook attempts as part of the message record.”
HMACsigned events
Replies routed into hosted product conversations.
“Receive normalized text, HTML, headers, and attachment metadata through email.received.”
INbound events
“Do not treat email as an invisible side effect. Give every message an identity, a state, and a safe retry path.”
POSTA PROTOCOLDelivery principle · version 1