Batch sending - SendFlit

POST /v1/emails/batch sends up to 100 emails in one call. It’s the right choice for many separate, one-recipient emails, such as a notification to each member of a team.

Send a batch

curl -X POST https://api.sendflit.com/v1/emails/batch \
  -H "Authorization: Bearer $SENDFLIT_KEY" \
  -H "Idempotency-Key: invoices-2026-09" \
  -H "Content-Type: application/json" \
  -d '{
    "emails": [
      {"from": "billing@yourdomain.com", "to": "a@example.com", "subject": "Invoice 101", "html": "<p>Invoice 101</p>"},
      {"from": "billing@yourdomain.com", "to": "b@example.com", "subject": "Invoice 102", "html": "<p>Invoice 102</p>"}
    ]
  }'

The body is an object with an emails array. Each message is independent. The response is {"results": [...], "count": N}, with one result per message in the same order. A message that succeeds has its id and status. A message that fails has "status": "failed", the to address, and an error, so one bad recipient doesn’t fail the rest.

Node.js
Python

const { results } = await sendflit.batch(messages, `invoices-${period}`);

results.forEach((r, i) => {
  if (r.error) console.error(`Message ${i} failed`, r.error);
});

res = sf.batch(messages, idempotency_key=f"invoices-{period}")
failed = [r for r in res["results"] if r.get("error")]

Limits and tips

Up to 100 messages per batch. Split larger lists into chunks.
Use one idempotency key for the whole batch, derived from the job, so a retried job doesn’t resend messages that already went out.
Check each result. Don’t assume the whole batch succeeded because the request did.
Quotas and rate limits apply to each message. See Limits.