SMS API

Optional gzip compression for campaign delivery

Aggregators can now opt in to gzip-compressed campaign delivery payloads by setting acceptGzipEncoding: true in the Handshake Endpoint request. Enabled endpoints receive a Content-Encoding: gzip header alongside the existing headers. The x-hub-signature HMAC is still computed over the uncompressed JSON, so decompress before verifying.

Impact: Optional for all aggregators. No action is required — omitting the field keeps the existing uncompressed behavior, and there is no deprecation timeline for the uncompressed path.

For full details, see the Handshake Endpoint guide.