A batch endpoint accepts many messages in one API request, each with its own recipient and text, and returns an individual result per message so that one invalid row does not fail the whole send.
Sending a campaign as ten thousand single requests is slow and hits rate limits; a batch endpoint takes up to a thousand messages per call with shared defaults (sender, campaign tag, schedule, pace) and per-message overrides. The important property is the response: accepted messages get ids, rejected ones get their error, in the same list.
Batches combine naturally with scheduling and pacing parameters, and with an idempotency key for the whole batch.
At SMSMeteor: POST /v1/messages/batch takes 1,000 messages per API request; rejections are listed individually since July 2026 instead of failing the batch.