4006: Spend limit exceeded.
The send would exceed a daily or monthly spend cap.
HTTP status: 422 or 429, depending on the request.
The projected charge would cross the account’s or number’s spend ceiling. With a known reset instant the response is 429 with Retry-After and error.retry_after naming the exact reset; without one it is 422 with neither. Nothing was journaled.
Troubleshooting
Section titled “Troubleshooting”- When error.retry_after is present, wait that many seconds; the reset is the UTC day or month boundary.
- A daily cap refuses any message carrying a template part; a message without one, such as a reply inside an open customer window, is still accepted past a daily cap and its charge still counts. The monthly cap refuses every send.