Check settings before you connect
From the Accounts API reference. Requests use the base URL https://app.warmerly.com/api/v1 and an API key, see Authentication.
POST /accounts/detect
POST /accounts/test-connectiondetect takes { "email": "you@yourdomain.com" } (3 to 320 characters) and returns { "detection": { … } }: Warmerly's best guess at the provider, from the domain's live MX records, with the SMTP/IMAP hosts and ports the dashboard's connect wizard would prefill. A domain it cannot place comes back as an unsupported kind with a human-readable note rather than an error.
test-connection takes full smtp and imap objects (host, port from 1 to 65535, user, pass, all required) and reports whether each side authenticated, without saving anything. Use it to surface a credential problem before creating an account that would immediately pause. Hosts that point at private or internal addresses are refused with 400 bad_request. On a failure, message is a plain-language reason; on success it is omitted.
{ "smtp": { "ok": true }, "imap": { "ok": false, "message": "Invalid credentials" } }