Add scheduled_at when Telnyx should accept an email now and queue it for a future time. This guide shows you how to schedule, confirm, and cancel a send—and how to avoid accidentally sending it immediately.
Step 1: Schedule with a future timestamp
Use the canonical scheduled_at field with a valid ISO 8601 timestamp in the future:
curl -X POST "https://api.telnyx.com/v2/email_messages" \
-H "Authorization: Bearer YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"from": "sender@mail.yourcompany.com",
"to": ["recipient@example.com"],
"subject": "Scheduled maintenance reminder",
"text_body": "Maintenance starts in one hour.",
"scheduled_at": "2030-01-15T15:00:00Z"
}'
A successful request returns 202 Accepted with status: "scheduled" and the stored scheduled_at timestamp.
Use scheduled_at for new integrations. send_at remains a deprecated request alias for backward compatibility, but responses use scheduled_at.
Avoid accidental immediate sends
The timestamp must parse as ISO 8601 and compare later than the current time. If it is invalid or already in the past, the Email API treats it as an immediate send: the response is queued instead of scheduled.
Always check both response fields before assuming the schedule was saved:
statusmust bescheduled.scheduled_atmust be present and match the intended instant.
Step 2: Confirm the schedule
Retrieve the message by ID:
curl "https://api.telnyx.com/v2/email_messages/{message_id}" \
-H "Authorization: Bearer YOUR_API_KEY"
Before the send fires, the message should remain scheduled. The scheduled_at field remains on the message after processing or cancellation, so use status to determine what happened most recently.
Step 3: Cancel before it is queued
Cancel the schedule with the message ID:
curl -X DELETE "https://api.telnyx.com/v2/email_messages/{message_id}/schedule" \
-H "Authorization: Bearer YOUR_API_KEY"
A successful cancellation returns 200 with status: "cancelled". Cancelling a message that is no longer scheduled returns 400; once delivery processing has begun, the schedule endpoint cannot recall the message.
There is no schedule-edit operation. To change the time, cancel the still-scheduled message and create a new scheduled send.
Check fire-time failures
Scheduled sends are accepted before they enter the delivery queue and are exempt from the submission-time recipient quota. Telnyx rechecks account eligibility and enforces the daily recipient limit when the schedule fires. The two fire-time rejection paths have different status outcomes.
If a scheduled message did not queue at the expected time, retrieve its events:
curl "https://api.telnyx.com/v2/email_messages/{message_id}/events" \
-H "Authorization: Bearer YOUR_API_KEY"
A daily_limit_exceeded event means the recipient quota was unavailable at fire time. The parent message becomes failed, while its recipient rows may remain queued. If account eligibility fails instead, recipient rows become failed and the parent message rolls up to completed. Neither path reaches the mail queue. Inspect the parent status, recipient_statuses, and event reason together; completed means all recipients are terminal, not that delivery succeeded.
Troubleshooting summary
Symptom | Cause and next step |
The response says | The timestamp was missing, invalid, or not in the future. The send was treated as immediate. |
The response omits | No future schedule was stored. Do not assume it will wait. |
Cancel returns | The message is not currently scheduled. Retrieve the message and inspect its status. |
The parent message becomes | This is the daily-limit rejection path. Inspect events for |
The parent is | Account-eligibility rejection marks recipient rows |