Scheduling Sends

Schedule emails for a future date and time with the POST /send-email endpoint. Specify the date with ISO 8601 timestamps or with natural language in English.

For bulk sends, POST /v1/send-batch also accepts scheduled_at in ISO 8601 format. See Public API v1.

Relevant fields

Field	Type	Description
`scheduled_at`	`string`	Send date and time. Accepts ISO 8601 or natural language in English.
`timezone`	`string`	IANA timezone name. Optional; only applies when `scheduled_at` is natural language.

`scheduled_at` format

ISO 8601 timestamps

Specify an exact date and time in ISO 8601 format. Always include the timezone offset (or Z for UTC). This is the recommended way to schedule an exact instant:

"2026-10-16T15:00:00+09:00"
"2026-12-25T09:00:00-03:00"
"2027-01-15T08:30:00Z"

With an ISO 8601 timestamp that includes an offset, the timezone field is ignored: the timestamp’s offset determines the send instant.

Natural language

You can also use natural-language expressions (in English). The API interprets them relative to the current moment:

"tomorrow at 3pm"
"in 2 hours"
"next monday at 9am"

With natural language, the timezone field (IANA name) defines the zone in which the schedule is confirmed (scheduled_for_local in the response). If not specified, the project’s default zone is used (default_timezone); if the project doesn’t have one, UTC is assumed. Always check the response’s scheduled_for field (UTC) to confirm the exact instant. For absolute precision, use an ISO 8601 timestamp with an offset.

`timezone` format

The timezone field accepts IANA timezone names:

Format	Example
IANA name	`"America/Santiago"`, `"Asia/Tokyo"`, `"Europe/Madrid"`
UTC	`"UTC"`

For a fixed UTC offset (for example -03:00), include it directly in the scheduled_at ISO 8601 timestamp instead of using the timezone field. If timezone is not included, the API uses the project’s default_timezone, or UTC if none is configured.

Validation

The date must be in the future. If scheduled_at resolves to a past date, the API returns 400 Bad Request with the message scheduled_at must be in the future.

Processing

Scheduled emails are processed in the background every 30 seconds. An email may be sent up to 30 seconds after the scheduled time.

Limitations

One recipient per scheduled send. If recipient is an array, only the send to the first recipient is scheduled.
cc, bcc, attachments, and senderName are not preserved in scheduled sends — they only apply to immediate sends.
Content is defined with html + subject, or with templateId (UUID of a template). The data object with variables is preserved and applied at send time.

Response

When an email is scheduled successfully, the response includes these fields:

Field	Description
`success`	`true` if the request was accepted.
`scheduled`	`true` when the email was scheduled (rather than queued for immediate sending).
`scheduled_send_id`	UUID of the scheduled email.
`scheduled_for`	Send date and time in UTC (ISO 8601).
`scheduled_for_local`	Send date and time in ISO 8601 with the offset of the timezone used.
`timezone`	Timezone used: IANA name, or offset label (e.g. `"UTC+9"`) when it comes from the ISO timestamp.
`message`	Confirmation message (in English).

Examples

Schedule with an ISO 8601 timestamp

curl -X POST https://api.reallyquickemails.com/send-email \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer sk_proj_xxxxxxxxxxxx" \
  -d '{
    "recipient": "customer@example.com",
    "sender": "sales@mystore.com",
    "subject": "Appointment reminder",
    "html": "<p>This is a reminder of your appointment tomorrow at 3:00 PM.</p>",
    "scheduled_at": "2026-10-16T15:00:00+09:00"
  }'

Response:

{
  "success": true,
  "scheduled": true,
  "scheduled_send_id": "a1b2c3d4-e5f6-7890-abcd-ef1234567890",
  "scheduled_for": "2026-10-16T06:00:00.000Z",
  "scheduled_for_local": "2026-10-16T15:00:00.000+09:00",
  "timezone": "UTC+9",
  "message": "Email scheduled for October 16, 2026 at 3:00 PM GMT+9"
}

Schedule with natural language and a timezone

curl -X POST https://api.reallyquickemails.com/send-email \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer sk_proj_xxxxxxxxxxxx" \
  -d '{
    "recipient": "customer@example.com",
    "sender": "sales@mystore.com",
    "subject": "Special offer",
    "html": "<p>Take advantage of our special offer this week.</p>",
    "scheduled_at": "tomorrow at 3pm",
    "timezone": "America/Santiago"
  }'

Response (illustrative values — they depend on when the request is made):

{
  "success": true,
  "scheduled": true,
  "scheduled_send_id": "b2c3d4e5-f6a7-8901-bcde-f12345678901",
  "scheduled_for": "2026-06-06T19:00:00.000Z",
  "scheduled_for_local": "2026-06-06T15:00:00.000-04:00",
  "timezone": "America/Santiago",
  "message": "Email scheduled for June 6, 2026 at 3:00 PM GMT-4"
}

Schedule with a numeric offset

The timezone field only accepts IANA names. For a fixed UTC offset, specify it directly in the ISO 8601 timestamp:

curl -X POST https://api.reallyquickemails.com/send-email \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer sk_proj_xxxxxxxxxxxx" \
  -d '{
    "recipient": "customer@example.com",
    "sender": "sales@mystore.com",
    "subject": "Follow-up",
    "html": "<p>We are following up on your request.</p>",
    "scheduled_at": "2026-10-20T09:00:00-03:00"
  }'

Response:

{
  "success": true,
  "scheduled": true,
  "scheduled_send_id": "c3d4e5f6-a7b8-9012-cdef-123456789012",
  "scheduled_for": "2026-10-20T12:00:00.000Z",
  "scheduled_for_local": "2026-10-20T09:00:00.000-03:00",
  "timezone": "UTC-3",
  "message": "Email scheduled for October 20, 2026 at 9:00 AM GMT-3"
}

Guides

The app

Concepts

API Reference

Relevant fields

`scheduled_at` format

ISO 8601 timestamps

Natural language

`timezone` format

Validation

Processing

Limitations

Response

Examples

Schedule with an ISO 8601 timestamp

Schedule with natural language and a timezone

Schedule with a numeric offset

​Relevant fields

​scheduled_at format

​ISO 8601 timestamps

​Natural language

​timezone format

​Validation

​Processing

​Limitations

​Response

​Examples

​Schedule with an ISO 8601 timestamp

​Schedule with natural language and a timezone

​Schedule with a numeric offset

Relevant fields

`scheduled_at` format

ISO 8601 timestamps

Natural language

`timezone` format

Validation

Processing

Limitations

Response

Examples

Schedule with an ISO 8601 timestamp

Schedule with natural language and a timezone

Schedule with a numeric offset