Create a new email broadcast. Broadcasts are created in DRAFT status — creating one does not send it. To send it, create a send action for the broadcast (POST /emails/broadcasts/{broadcast_id}/send_actions): omit send_at to send now, or pass a future send_at to schedule. (Alternatively, the legacy inline path accepts recipients with send_immediately=true, or send_at/send_at_local_time/time_zone to schedule.) A complete business mailing address is required even when creating a draft. Configure it first with PUT /workspaces/{workspace_id}/emails/settings; an incomplete address returns 422. When accessing the API through an OAuth connection from a third-party platform, this endpoint is restricted to trusted developer platforms. If you are using your own API key, you can send emails directly from your account. Pick from_email and reply_to_email from addresses whose top-level usable_as_sender is true, not from the sending domain's verified flag: verified covers email transport only, and sending a broadcast from an address that is not usable is rejected with 422. List addresses via GET /workspaces/{workspace_id}/emails/addresses. See Broadcasts and the Business mailing address prerequisite in the Emails Skill.