MX lookup

Find the mail servers responsible for a domain

What is an MX lookup? Mail Exchanger (MX) records tell email delivery agents where to route emails for a specific domain. This tool queries the MX records, resolves their underlying IP addresses, and allows you to quickly run blacklist or port scans against them.
Enter a domain above to get started.

MX priority

Each MX record has a priority number. Sending servers try the lowest number first; records with the same number share the load, and higher numbers act as backups.

Recognising the email provider

When a security gateway (Sophos, Mimecast, Proofpoint) appears in the MX, mail passes through it before reaching the mailbox provider behind it.

No MX records?

Without MX records, senders fall back to the domain’s A record (RFC 5321), which is rarely what you want. A “null MX” — priority 0 pointing to . — says the domain accepts no email at all.

Next steps

Check the mail servers’ IPs with the Blacklist check, and the domain’s SPF, DKIM and DMARC with the Domain trust report.