implicit_mx

The domain has no MX record and relies on the address-record fallback

The domain publishes no MX record, so mail would fall back to its own address under RFC 5321; such web-only domains rarely accept mail and are never probed.

risk weight: +30
dataset: live-dns
reads from: mx_implicit
verdict reason: implicit_mx

What it means

RFC 5321 lets a domain without MX records receive mail at its A or AAAA record. Almost no domain set up that way runs a mail server, so the handshake is skipped and the address is reported as risky rather than tried.

It reads from the mx_implicit field and comes with the implicit_mx verdict reason.

What to do

Expect a bounce; at signup, ask for another address.

Example response

{
    "email": "[email protected]",
    "deliverable": "risky",
    "reason": "implicit_mx",
    "mx_found": true,
    "mx_implicit": true,
    "risk_signals": [
        {
            "signal": "implicit_mx",
            "weight": 30,
            "dataset": "live-dns"
        }
    ]
}

Abbreviated: a real answer carries all 46 fields, listed in the verify-email reference. The risk_signals entry shown is the one this signal adds; the weights of every entry in the list sum to risk_score.

markdown version: /docs/signals/implicit_mx.md

implicit_mx

What it means

What to do

Example response

Related