Error codes
not_found
HTTP status: 404
What happened
The endpoint or the resource does not exist for this account.
A send whose sender domain was never added, was deleted, or belongs to another tenant also returns this error. The message names the domain. It does not ask for DNS records.
How to fix
Check the path and the resource ID prefix (em_, dom_, key_, wh_, whd_).
For a sender domain, add the domain in Domains, then send again.
Source: docs/errors/not_found.md.