About the MX Lookup
MX Lookup finds the mail servers for a domain and checks the DNS settings that decide whether its email is delivered and trusted. It lists each MX record with its priority and the IP addresses of the mail server, then checks for an SPF record, a DMARC policy and, if you enter a selector, a DKIM key. Each check is marked OK, Warning or Problem with a plain explanation. It reads public DNS only, through Cloudflare's DNS over HTTPS with Google's as a backup, and does not send any test email.
Updated October 2026
How to use the MX Lookup
- 1Type the domain, such as example.com. A full email address or web address also works.
- 2Optionally enter a DKIM selector such as google or selector1.
- 3Press Check email setup.
- 4Read the mail servers and their priorities.
- 5Work through any Warning or Problem in the checks and press the button again after you fix it.
How email finds your server
When someone sends a message to [email protected], their mail server asks DNS for the MX records of example.com. It tries the server with the lowest priority number first, then the others if the first does not answer. If there are no MX records at all, it falls back to the domain's own address, which is called an implicit MX.
SPF, DKIM and DMARC
Three records work together to prove that email really comes from your domain. SPF lists the servers allowed to send. DKIM adds a signature to each message. DMARC ties them together and tells receivers what to do when checks fail. Setting all three up improves delivery and protects your domain from being used in scams.
- SPF: one record, ends with -all or ~all
- DKIM: a public key under selector._domainkey
- DMARC: start with p=none, then move to quarantine or reject
- Add a report address (rua) to see who sends as your domain
Fixing common problems
Two SPF records is the most common error: merge them into one. +all lets anyone send as you, so replace it. DMARC p=none is a good start but protects nothing, so plan to tighten it once reports look clean. A mail server with no IP address cannot receive mail, so fix its A or AAAA record or point MX to a different host.
After you change DNS
DNS changes take time to spread, up to the TTL of the old record. Check again after a few minutes, and use the DNS Lookup to see the raw TXT records. If you move email providers, lower the TTL a day before so the switch happens quickly.
Related tools
The DNS Lookup shows all record types for a domain. To write messages that are less likely to be flagged, use the Email Subject Line Generator and the AI Email Writer, and for what your server answers over the web, try the HTTP Header Lookup.
Features
- MX records with priority and IP addresses
- SPF record check: missing, duplicated, +all, ~all, lookup limit
- DMARC policy check with report address
- Optional DKIM key check by selector
- Detects null MX and implicit MX
- Copy the report
Frequently asked questions
What is an MX record?
A mail exchanger record names the server that accepts email for a domain. A domain can have several, each with a priority; senders try the lowest number first and fall back to the others.
What is SPF?
A DNS record that lists which servers may send email for your domain. Receiving servers check it to spot forgeries. It must be a single TXT record starting with v=spf1 and normally ends with -all or ~all.
What is DMARC?
A policy, published at _dmarc.yourdomain, that says what receivers should do with mail that fails SPF and DKIM checks (none, quarantine or reject) and where to send reports. Large mailbox providers now expect bulk senders to have it.
What is DKIM and why do I need a selector?
DKIM signs outgoing mail with a key. The public key sits in DNS under a name made from a selector chosen by your email provider, such as google._domainkey. Without the selector the tool cannot know which name to check.
My MX records look right but mail still fails. Why?
Other problems exist: a full mailbox, a firewall, a typo in the address, or a sending server being blocked. DNS is only one part. Check bounce messages for the exact reason.
What is a null MX?
A record with priority 0 and a single dot that says the domain never receives email. It is used for domains that only send or only host a website.
Does it test whether the mail server answers?
No. It reads DNS records only. It does not connect to the mail servers or send a message.
Is my domain stored?
No. The lookups run from your browser to Cloudflare's DNS service, or Google's if needed. We do not keep them.