Email host lookup
The MX records say who receives mail for a domain, and the answer is often not what the brand suggests: a company can be on Microsoft with a filtering service in front, or on nothing at all.
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Why the host matters before you send
Different receivers behave differently in ways that decide whether your mail lands. Microsoft weights domain reputation heavily and is unforgiving of new sending domains; Google leans on engagement signals; corporate filtering layers apply rules nobody outside the company can see. Knowing which one you are talking to explains a lot of otherwise mysterious deliverability, and it tells you whose postmaster documentation to read when something goes wrong.
What MX cannot tell you
It identifies the servers that accept mail for the domain, not the mailbox behind them, and not whether a specific address exists. A domain can have flawless MX records and reject every message you send. Nor does MX reveal where mail goes after acceptance: a filtering front end forwards to somewhere else entirely, and that hop is invisible from outside.
Questions
The domain has no MX record. Can I still email it?
Sometimes. Receivers may fall back to the A record, but many do not, and a domain without MX is usually one that never intended to receive mail. Treat an address there as unlikely to work.
Why are there several MX records with different numbers?
The number is a preference: lower is tried first, and the others are fallbacks. Equal numbers share the load. A single MX is a single point of failure, though a well-run one is often more reliable than several badly-run ones.
Related tools
MX record lookup
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Catch-all domain checker
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Email deliverability check
One check for MX, SPF, DMARC and DKIM on your sending domain, with what to fix first. Free, no signup.
When you need more than a free tool
This page answers what can be determined offline and from public DNS. The API adds live carrier and mailbox verification, a calibrated confidence score, and the full evidence trail behind every verdict.
Credits never expire. Inconclusive verdicts are never billed. Cancel in one call. See pricing or read the docs.