Look up any domain's mail servers for free: its MX records, their priorities, and the email provider that hosts them. It also checks SPF and DMARC in the same pass, so you see the whole mail setup. No sign-up.
An MX (Mail eXchange) record is a DNS entry that names the mail servers responsible for receiving email for a domain. When a server needs to deliver a message to jordan@acme.com, it looks up acme.com's MX records to find where to send it. Each record has a priority (the lowest number is tried first), which lets a domain list a primary server plus backups. A missing MX can allow an A or AAAA fallback; a null MX explicitly refuses mail. These different outcomes are defined in the null MX standard (RFC 7505).
An MX lookup returns a list of mail servers with priorities. Here is what each part means.
| Term | What it means |
|---|---|
| Mail server (exchange) | The hostname that accepts mail for the domain, like aspmx.l.google.com. Sending servers connect here to deliver. |
| Priority | A number that orders the servers: the LOWEST number is tried first. Lower means higher priority. It is preference, not quality. |
| Backup / secondary MX | A higher-priority-number (lower-preference) server used only when the primary is unreachable, so mail queues instead of bouncing. |
| Provider | Who runs the mailbox. The MX hostnames reveal it: Google Workspace, Microsoft 365, Proofpoint, and so on. |
| Implicit MX | With no MX record, senders can try the domain's A or AAAA address. This lookup does not test whether that address accepts SMTP connections. |
| Null MX (0 .) | An explicit declaration that the domain accepts no mail. It must be the only MX record, with priority 0 (RFC 7505). |
Type any domain (like acme.com). You can also paste an email or URL and the tool extracts the domain. Only public DNS is read.
See each MX host, its priority (lowest is tried first), and the recognized email provider, plus the domain's SPF and DMARC status.
A null MX refuses email. Missing MX records may allow an address fallback. Unavailable means retry. Published mail servers do not prove a mailbox exists.
Yes, and it needs no sign-up. It reads the domain's public DNS to list its MX records, their priorities, and the likely email provider, then checks SPF and DMARC in the same pass. Nothing to install, nothing to pay.
An MX (Mail eXchange) record is a DNS entry that names the mail servers responsible for receiving email for a domain. A sending server looks up the recipient domain's MX records to find where to deliver mail. A missing MX record can trigger an A or AAAA fallback; a null MX explicitly says the domain accepts no mail.
Each MX record carries a priority number, and the lowest number is tried first. So 10 is preferred over 20. Priorities let a domain publish a primary mail server plus one or more backups (higher numbers) that only receive mail when the primary is unreachable, so messages queue rather than bounce. Equal numbers share load.
For redundancy and load. Multiple MX records at the same priority spread incoming mail across servers; records at higher priority numbers act as backups. A domain can use more than one provider, so the provider label inferred from its preferred MX is only a clue.
Usually yes. The MX hostnames give it away: aspmx.l.google.com means Google Workspace, mail.protection.outlook.com means Microsoft 365, and names containing pphosted, mimecast or barracuda point to those security gateways in front of the real mailbox. This lookup labels the provider for you when it recognizes the host.
Yes. With no MX record, senders may try the domain's A or AAAA address as an implicit mail server (RFC 5321). The address still needs a working SMTP service. This checker does not test that fallback, so 'no MX' alone is not proof that delivery is impossible.
A single MX record with priority 0 and exchange . declares that the domain does not accept email (RFC 7505). Senders must not use an A or AAAA fallback. This can be intentional for a domain that does not use email, even when it publishes SPF and DMARC to discourage spoofing.
No. It means the DNS lookup failed or timed out. The report keeps any checks that succeeded and marks the others unavailable. Retry before changing DNS settings; incomplete results are not cached by this tool.
MX records are about receiving mail, so they do not authenticate outbound messages. This tool also reads SPF and DMARC. It does not check DKIM signatures, SMTP availability, mailbox existence, or inbox placement.
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