Free DNS tool
MX Lookup
See which mail servers accept email for any domain, in priority order, and spot the problem behind bouncing mail.
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Lookups run in your browser over Google public DNS-over-HTTPS (Cloudflare as fallback). Nothing you enter is sent to Pulsetic.
Email only works while your mail hosts do. Pulsetic monitors the servers behind your MX records and alerts you the moment one stops responding.
What is an MX record?
An MX (mail exchange) record tells other mail servers where to deliver email for your domain. Each MX record points at a mail server host name and carries a priority number; senders try the lowest number first and fall back to higher ones if it is unreachable.
A domain can have several MX records for redundancy. The host names they point at must themselves resolve to an A or AAAA record, and an MX must never point at a CNAME, which the mail standard forbids.
How to read MX lookup results
Each row shows a priority and a host. "10 aspmx.l.google.com" means priority 10, server aspmx.l.google.com. Lower wins, so 1 is tried before 10. If two records share a priority, mail is balanced across them.
No MX record at all means mail falls back to the domain A record, an implicit MX that is rarely what you want. If email is bouncing, confirm the MX hosts resolve and that your SPF and DMARC TXT records line up with the servers actually sending your mail.
Look it up from the terminal
Prefer the command line? These return the same records this tool shows:
dig example.com MX +short
nslookup -type=MX example.com
Every DNS record type
What each record does. Each one has a dedicated lookup in the tabs above.
| Record | What it does | Example value |
|---|---|---|
| A | Maps a domain to an IPv4 address. | example.com → 93.184.216.34 |
| AAAA | Maps a domain to an IPv6 address. | example.com → 2606:2800:220:1:: |
| CNAME | Points one name at another name, as an alias. | www → example.com |
| MX | Names the mail servers that accept email for the domain, each with a priority. | 10 mail.example.com |
| TXT | Holds free-form text, used for SPF, DKIM, DMARC and domain verification. | v=spf1 include:_spf.google.com ~all |
| NS | Lists the authoritative name servers for the domain. | ns1.example.com |
| SOA | Start of authority: the primary name server and the zone refresh, retry and expiry timers. | ns1.example.com . 2026010101 |
| PTR | Reverse record: maps an IP address back to a host name. | 34.216.184.93.in-addr.arpa |
| SRV | Locates the host and port for a specific service. | _sip._tcp → 5060 sip.example.com |
| CAA | States which certificate authorities may issue SSL certificates for the domain. | 0 issue "letsencrypt.org" |
Frequently asked questions
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What is an MX record?
An MX record names a mail server that accepts email for a domain, together with a priority. Lower priorities are tried first, so a backup server can sit at a higher number and take over only when the primary is down.
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Why is my email bouncing if the MX record looks right?
Check that each MX host resolves to an A or AAAA record and is not a CNAME, which is not allowed for MX targets. Then confirm your SPF and DMARC TXT records authorize the servers that actually send your mail, since delivery failures are often an authentication problem rather than a missing MX.
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What do the numbers in front of MX records mean?
They are priorities. A sender contacts the lowest-numbered server first and moves to the next only if it cannot connect. Equal numbers spread the load across those servers.
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Can a domain have more than one MX record?
Yes, and most do. Multiple MX records give you redundancy: if the primary mail server is unreachable, senders retry the next priority until one accepts the message.
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