What is an MX record?
An MX (mail exchanger) record tells the world which servers accept email for a domain. When someone sends a message to you@example.com, their mail server looks up the MX records for example.com and delivers to the listed host with the lowest priority number first. If that server is unreachable it tries the next one. Records with equal priority share the load.
How to read MX lookup results
- Priority: lower is preferred.
10is tried before20. - Mail server: must be a hostname with an A or AAAA record. It must never be an IP address or a CNAME.
- IP addresses: where the server actually lives. Click one to geolocate it.
- Provider: we recognise common platforms such as Google Workspace, Microsoft 365, Proofpoint, Mimecast, Zoho and Fastmail from the hostname.
- Null MX: a single record of
0 .(RFC 7505) means the domain deliberately accepts no email.
Common MX problems
- No MX records after moving DNS hosts. Copy the records from your email provider's setup guide.
- MX pointing to a CNAME or an IP address, which violates the standards and is rejected by some senders.
- Old records left behind when switching providers, so some mail goes to the old system.
- Missing SPF/DMARC. MX only covers incoming mail; outgoing mail is authenticated separately. Test it with our SPF & DMARC checker and read SPF, DKIM and DMARC explained.
Frequently asked questions
How long do MX changes take?
As long as the old record's TTL, typically between five minutes and a few hours. Check with the propagation checker.
Can I look up MX records from the command line?
Yes: nslookup -type=mx example.com on Windows or dig mx example.com +short on macOS and Linux.