MX Lookup

About the MX Lookup tool

This tool lists the mail exchanger (MX) records of a domain in priority order, exactly as a sending mail server would see them. The lookup goes directly to the domain’s authoritative name servers, so a change you published a minute ago shows up immediately — no waiting for resolver caches to expire.

For every MX host we also resolve the IPv4/IPv6 addresses, look up the reverse DNS (PTR) record, and run each address through 60+ DNS blacklists. Warnings are raised for missing reverse DNS, MX targets that point at IP addresses or CNAMEs, private addresses, and single-server setups without a backup.

Common problems it finds

• No MX records — mail falls back to the A record, which is rarely what you want.
• MX host does not resolve — a typo or a decommissioned server silently bouncing mail.
• Missing PTR — Gmail, Outlook and most enterprise gateways penalise servers without forward-confirmed reverse DNS.
• Blacklisted MX IP — usually a shared host or a compromised mailbox.

Next steps: click Test SMTP on a result to connect to the server and verify STARTTLS and open-relay behaviour, or run the Email Health report for the full picture.