MX lookup
See which servers receive mail for a domain, and which provider handles it.
About MX lookup
What it is
The MX records (Mail Exchange) in a domain's DNS point out which servers receive mail for the domain, and in what order. They are what determines where an email to you is actually delivered.
Why it matters
Incorrect or missing MX records cause mail to bounce or disappear. The MX records also reveal which provider you use (Microsoft 365, Google Workspace or another), which is the starting point for all further email security.
Tips
- Have at least two MX records for redundancy in case one server does not respond.
- The lowest priority number is used first, so make sure it points to the right place.
- Point MX directly at your provider's servers, not at an old or self-hosted server.
Common questions
What is an MX record?
An MX record is a DNS record that specifies which server receives mail for a domain, and with what priority.
How can I see which email provider a domain uses?
By looking up the domain's MX records. If they point to outlook.com it is Microsoft 365, and if they point to google it is Google Workspace.
More lookups
SPF check
Check whether a domain has an SPF record and how strictly it rejects spoofed mail.
DMARC check
See whether a domain has DMARC and which policy it uses against spoofed mail.
DKIM check
Look for DKIM signing on a domain using the most common selectors.
DNSSEC check
See whether a domain is protected with DNSSEC, that is, whether its DNS answers are signed.
TXT lookup
List all TXT records for a domain, including SPF, verifications and more.
NS lookup
See which name servers control a domain's DNS.
Blacklist check
Check whether a domain's IP address is on blacklists such as Spamhaus, Barracuda and SpamCop.
A/AAAA lookup
See which IP addresses a domain points to, both IPv4 (A) and IPv6 (AAAA).
CNAME lookup
See whether a domain is an alias that points on to another domain.
SOA lookup
See the zone's core data: primary name server, contact and serial number.
CAA lookup
See which certificate authorities are allowed to issue certificates for the domain.
Reverse DNS (PTR)
Look up which host name a domain's IP address points back to.
MTA-STS
See whether a domain requires encrypted mail delivery via MTA-STS.
TLS-RPT
See whether a domain receives reports about failed encrypted mail delivery.
BIMI
See whether a domain publishes a logo that can be shown in the recipient's inbox.
SSL certificate
Check a domain's TLS certificate: issuer, validity and expiry.
Whois
See who owns a domain, when it was registered and when it expires.
HTTP security headers
Check whether a domain's website sets important security headers.