Sends

Every send, reply, forward or draft send returns a send_id (out_…). It is the release service’s record of that message.

Get a send

GET/v0/sends/{send_id}

Permission message_read.

{
  "send_id": "out_01JZX4C0D1E2F3G4H5J6K7M8N9",
  "inbox_id": "shop-helper@simail.email",
  "thread_id": "thr_01JZX4C0D1E2F3G4H5J6K7M8NB",
  "message_id": "msg_01JZX4C0D1E2F3G4H5J6K7M8NA",
  "status": "pending_approval",
  "reasons": [],
  "flags": ["first_contact"],
  "approval_id": "apr_01JZX4C0D1E2F3G4H5J6K7M8NG",
  "send_at": null,
  "created_at": "2026-10-18T17:05:40Z",
  "updated_at": "2026-10-18T17:05:40Z"
}

Status

status	Meaning	Final
checking	being checked
scheduled	waiting for send_at
pending_approval	waiting for a human
approved	approved; waits for the final check
sending	leaving now
sent	handed to the mail network	yes
blocked	refused; reasons says why	yes
rejected	an approver rejected it	yes
expired	nobody approved it in time, or it waited too long for a limit or a lock	yes
cancelled	cancelled before sending	yes
failed	the mail network refused it; submit again with a new key if you still mean to	yes
outcome_unknown	it may or may not have gone out; never resent automatically, corrected when a delivery event arrives

checking → blocked | pending_approval | scheduled | approved
pending_approval → approved | rejected | expired | cancelled
scheduled | approved → sending → sent | failed | outcome_unknown | blocked
scheduled | approved → cancelled

While a message waits (platform pause, organization pause, thread lock, daily limit), it stays scheduled or approved and a send.deferred event says why.

Cancel a send

DELETE/v0/sends/{send_id}

Permission message_send. Cancels a send that is scheduled, pending_approval or approved. Returns the send with status: "cancelled" and publishes send.cancelled. If it is already sending or final, returns 409 conflict with reason: "already_sending" or "already_final".

Errors: 404 not_found (unknown or outside your scope), 409 conflict.

MCP: get_send_status.