Send an email card

Approve and send an email draft or reply Revnu wrote, optionally with an edited reply body. This sends real email.

Requires the review:write scope.

Response. 200 { "ok": true, "data": { "outcome": "sent", "queued": false, "messageId": "<id>" } } once the provider accepted it; messageId is the delivery receipt. When the mailbox paces its sending, the email is queued instead: data has queued: true and, once the queue has placed it, leavesAt (ISO 8601) and timing. A provider refusal is also a 200, as { "ok": false, "error": { "kind", "detail" } }; kind is one of rate_limited, out_of_credits, not_found, network, upstream_5xx, schema_drift, bad_input, missing_key or budget_exhausted. The full shape is in /openapi.json. 409 if the card was already handled or is not an email card. 503 delivery_pending with a Retry-After header if the provider's answer was lost: the send is fenced for reconciliation rather than risked twice, so wait and retry the same call. 503 unavailable, also with Retry-After, when the delivery service could not be reached.