Confirm the result of the single reserved mail attempt.

Private and no-store. Accept enviado, adiado, rejeitado or incerto. enviado means provider acceptance, not inbox delivery. adiado is valid only when no send occurred: retry after one hour, with at most six reservations. rejeitado discards the notice. incerto prevents automatic resend. A late matching receipt can confirm an uncertain send. Exact confirmation replay does not write or extend a deadline. Returns: { estado }