vocapablewebhook_destination_url_invalid
In production every DNS answer is checked at save time; the transport re-resolves and pins a vetted public address at send time and never follows redirects.
Problem shape
Every non-2xx response is an RFC 9457 application/problem+json body. The type URI below is stable and machine-matchable, so branch on the final path segment (the code) and treat the status as redundant confirmation. See the error-handling guide.
{
"type": "https://docs.vocapable.com/errors/webhook_destination_url_invalid",
"title": "…",
"status": 422,
"detail": "…",
"instance": "/v1/…"
}