There is a single current API — no /v1, /v2 split. New fields and endpoints are additive; existing fields are never renamed or removed without advance notice here first.
Realtime events over SSE — GET /stream carries the same payloads webhooks POST, with per-key scoping and inbox/type/cursor filters. Message labels + search on inbox messages, with dashboard filter, chips, and editor. HITL draft approval — stage a send, approve it (single-flight) or withdraw it, from the API, SDK, dashboard, and MCP (create_draft → approve_draft). One-click role addresses — create the inbox and its forward in one dashboard step. OpenAPI at GET /openapi.json documents all 35+ public operations.
Delivery events from our own mail server (queued → sent → delivered, proven — not assumed). Cancel a scheduled send. Threaded conversations. Webhook signature verification in the SDK. Email verification gate on sending, per-project quotas, and abuse screening on the send path.
Lives in git. Anything older than this page that matters to your integration is still additive — if a change ever needs your action, it will be announced here first with a migration window.