MX Lookup — Where Your Mail Is Actually Delivered
MX records tell the world which servers accept mail for your domain, and in what order to try them. This lookup returns those records with their priority values and confirms each named host resolves to an address. It is the first question in any mail investigation, because every other consideration is downstream of mail reaching the right server.
Why run it
MX misconfigurations produce some of the most alarming failures in infrastructure, because mail sent to a wrong or hostile destination is simply gone — no bounce, no trace, no recovery. Common findings are a backup MX pointing at a host that was decommissioned years ago, priorities inverted so that a fallback receives primary traffic, or records still listing a provider you migrated away from. All of them look fine until the specific circumstance that exercises them.
Why automate it
Changing MX records is how mail gets stolen. It is a standard step in domain compromise precisely because it is quiet: mail flows to an attacker, and optionally onward to you, so nobody notices anything missing. There is no internal signal for this at all — your systems are fine, your users receive mail. Continuous monitoring that alerts on any change to MX records is one of the highest-value checks available relative to its cost, and it doubles as a safety net for changes made legitimately but without telling you.
What it gives you
Certainty about where your mail is delivered, and immediate notice when that answer changes. Given that the failure modes range from silent loss to interception, this is not a check to leave to the memory of whoever last touched DNS.