Skip to main content
Most of the API shares a single response envelope; a few endpoint groups wrap responses differently. All of them use standard HTTP status codes — check those first.

​
Status codes

429 is not a general throttle on the API. It is returned only by the endpoints authenticated with the securityToken header / Bearer / userSecurityToken forms — in the public API, logo and receipts — after 30 failed authentication attempts from the same IP within one hour. The letter, e-mail and WhatsApp endpoints do their own authentication and never answer 429.

​
Envelopes

Used by the Letters/Telegram (v2), Registered E-mail, Receipts (errors) and WhatsApp message and sender endpoints. status mirrors the HTTP status code, and status_message carries the reason on an error.
The envelope’s status / code field always mirrors the real HTTP status code — errors are never wrapped in an HTTP 200.

​
Request ids

Endpoints using the standard envelope also return an X-Request-ID response header:
Quote it when reporting a problem — it is the key to the server-side log for that exact call. The WhatsApp template endpoints return the same identifier as request_id in the body instead of the header. Favorites and the number check return neither.