Send an email

Sends an email design. Polymorphic on the test flag:

• test: true → a synchronous one-off TEST delivery of the design’s current (or pinned) body to a single address. Forces the Brew default sender (no verified domain needed), targets one to address, and never creates a Send row. Returns 200 { status: "sent", recipient }.
• default / test: false → a campaign send combining the design (emailId, optionally pinned to emailVersionId), a verified domainId, and a target — a saved audienceId OR inline to (a single email or an array, max 50) — into one delivery event. The same design can be sent unlimited times; every call mints a new send. Returns 202 { sendId, runId } — poll via GET /v1/analytics/sends?sendId=.

Campaign target — provide EXACTLY ONE of audienceId or to. Inline recipients face the same unsubscribe/suppression gate and per-recipient quota as audience sends. For per-recipient event-driven delivery, publish an automation and fire its trigger (POST /v1/automations/triggers/{triggerEventId}/fire).

Brand scoping: resources (emailId, domainId, audienceId) living in a different brand surface as 404 so the API never confirms cross-brand existence.