Angola
Brasil
Kenya
Moçambique
Nigeria
Portugal
South Africa
United Kingdom
United States
International
The short answer: POST /v1/email/messages/batch sends many e-mails in one request. Fields outside messages apply to all of them, and each message has its own to and variables. There is no limit on the number of messages, only on the request size (8 MB). results says what happened to each one.
An example
curl https://api.mozout.com/v1/email/messages/batch \
-H "Authorization: Bearer sandbox_..." \
-H "Content-Type: application/json" \
-H "Idempotency-Key: invoices-2026-11" \
-d '{"from": "Your Company <invoices@yourcompany.com>",
"template_id": 12,
"messages": [
{"to": "ana@example.com", "variables": {"name": "Ana", "number": "FT 214"}},
{"to": "rui@example.com", "variables": {"name": "Rui", "number": "FT 215"}}]}'
The shared fields are from, subject, html, text, template_id, reply_to and send_at. Each message can change any of them, and follows the same rules as a normal send.
Reading the answer
| Field | What it says |
| total | How many messages the request had |
| accepted / rejected | How many were accepted and how many refused |
| credits | The credits used |
| results | One line per message, in request order: index, id, status and, if it failed, error and field |
A message with an invalid address comes back with "status": "rejected" and "error": "invalid_recipient", and the others go ahead anyway. Use the index to find which one to fix.
What goes at once and what joins the queue
The first 20 messages go out straight away; the rest join the queue, which runs every minute. So a big batch takes a few minutes to go out completely: follow each id in the log or through the webhook.
| Without credits or at the daily limit, the rest are refused. If the balance runs out or the daily limit is reached part-way, the remaining messages come back as rejected, with the reason insufficient_credits or daily_limit_reached. Check your balance before a big batch: credits and the daily limit. |
| A batch is for individual messages. Each person gets their own invoice or notice. The same news for your whole list is a campaign, with an unsubscribe link: see e-mail marketing. |
|
Want to send all of this month’s invoices at once? See the API page. See the API page |
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