4006: Message send timed out

The send did not complete within the expected time. Delivered asynchronously as a message.failed webhook. The message may still go out after this event fires — a message.sent or message.delivered webhook for the same message ID can follow. Failures of this class were previously reported under the generic 4001.

• Wait briefly for a message.sent or message.delivered webhook; if none arrives, retry with a new idempotency key (reusing the original key returns the stored failed message without sending)
• If timeouts persist on one sender line, check that line’s status in your dashboard