MX record lookup
Shows a domain's mail servers with the priority of each. The lower number is tried first; the later records are only used when the first does not answer.
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What the MX record lookup shows
An MX record lookup lists the mail servers a domain publishes for receiving mail, each with its priority and TTL. The query goes to Cloudflare's 1.1.1.1 from the IPVIEW server over the toolkit's own DNS engine, UDP first and TCP if truncated, so what you see is what a public resolver, and therefore a sending mail server, is told.
The value shows the preference and the exchange, for example 10 mx1.example.net. The lower number is tried first; higher numbers are used only when the first does not answer, and equal numbers share the load. The exchange is a name, not an address; to see where mail actually goes it has to be resolved in turn, which the Full report does for the first ten.
How to read the result
The table lists Name, Value and TTL. An empty answer is read from the response code. No MX record means the zone answered and has none; a sender then falls back to the domain's A record, which is rarely what anyone intended. The name does not exist at all means NXDOMAIN. The query failed means no answer was had, and nothing about the domain's mail follows. The TTL here is the time left on 1.1.1.1's cached copy and can be lower than the TTL set in the zone; the Full report asks the zone's own nameservers for that.
Mistakes visible here: an exchange that is an IP address, which many receivers refuse; an exchange that is a CNAME, which the standard forbids; two sets of records left from a half-finished migration, so some mail still goes to the old provider; a very long TTL, which makes a change of provider take that long to reach every sender.
When it is useful
Mail to the domain is bouncing or vanishing: see which servers senders are told to deliver to, then check that each exchange resolves (A record), answers on port 25 (Check one port) and has a reverse name (Reverse DNS). If the records point at a previous provider, nothing on the new one will help.
During a move to a new mail provider, to confirm the new records are published with the right priorities and the old ones are gone. For the sending side, SPF, DKIM and DMARC, the Email security check reads the records that decide whether the domain's own mail is accepted.
Common questions
What does the number in an MX record mean?
The priority. Senders try the lowest number first and move to higher numbers only if that server does not answer; equal numbers are tried in turn, which spreads the load.
My domain has no MX record. Does mail still arrive?
By the standard a sender falls back to the domain's A record on port 25. In practice many providers refuse to deliver that way; publish an MX record for any domain meant to receive mail.
Can an MX record point at an IP address?
It must point at a hostname with an A or AAAA record, and that hostname must not be a CNAME. An address in the exchange field is a misconfiguration many receivers will not deliver to.
How long does an MX change take?
Up to the TTL set in the zone, counted from when a sender last cached the old record. The number on this page is the time left on 1.1.1.1's copy; the Full report shows the zone's own. Keep the old servers accepting mail for at least that long.
Limits. The DNS, WHOIS and SSL tools allow up to 20 requests a minute per IP address. Ping, traceroute and MTR send real packets to their target, so they allow 6 a minute.
The port check runs only against your own IP address. That is deliberate: the question people actually have, "is this port reachable from outside?", is answered by it, while this server cannot be used to scan anyone else's network.
Private and reserved addresses. These are refused by the tools that really connect to their target: the SSL check, ping, traceroute, MTR and the port check. The DNS tools have no such limit, because they only ask a nameserver a question and never connect to the address itself.