MX record check: test a domain's mail servers
Find out which servers accept a domain's email, in which order they are tried and whether each of them can be reached.
Look up MX records
Enter the domain whose incoming email you want to check, for example your-domain.co.uk.
Lookups run through the Quad9 DNS resolver (Switzerland). We keep the checked domain and an anonymised IP address for no longer than 30 days.
How MX records work
What is an MX record?
MX stands for mail exchanger. The record tells other mail servers where to deliver email for your domain. When someone sends a message to info@your-domain.co.uk, their server looks up the MX records of your-domain.co.uk via DNS and delivers the message to the server listed there.
Priority and backup servers
Every MX record has a priority. The lowest number wins: a server with priority 10 is tried before one with 20. If the first cannot be reached, the sender tries the next. If several records share a priority, the load is spread randomly between them.
What the MX check tests
We show every MX record sorted by priority and resolve each mail server. An MX must point to a hostname with an A or AAAA record – not directly to an IP address and not to a CNAME. We also warn you if a mail server points to a private address that cannot be reached from the internet.
Common MX mistakes
MX points to an IP address
An MX record must contain a hostname such as mail.your-domain.co.uk. Add the IP address as an A record for that hostname and refer to it in the MX.
MX points to a CNAME
According to the standard, the target of an MX must not be an alias. Many servers deliver anyway, some do not. Point directly to the hostname with the A record instead.
Mail server does not resolve
If an MX points to a name that does not exist, email goes nowhere or sits in queues for days. This often happens after a change of provider.
No MX record at all
Without MX, senders try to deliver your email to the address of the A record. If no mail server runs there, email never arrives. If you deliberately do not want to receive email, set a null MX (0 .).
Frequently asked questions
Enter your domain above. The MX check shows every mail server with its priority and tests whether it can be reached. You can change the records in the DNS management of your host or domain provider.
Technically one is enough. Large providers such as Google or Microsoft often list a single hostname backed by many servers. If you run your own mail servers, a second record with a higher priority number adds redundancy.
That is the priority. The smaller the number, the sooner the server is tried. The absolute value does not matter, only the order: 10 and 20 work exactly like 1 and 2.
That depends on the TTL of the old record. Until it has expired, some servers still deliver to the old mail server. So keep the old server running for a day or two after a move.
A null MX is a single record 0 .. It tells every sender that the domain does not accept email. That makes sense for domains used only for websites and stops messages sitting in queues.
No. MX only governs incoming email. For your own email to be delivered, you also need SPF, DKIM and DMARC. Test them with the SPF check and the DMARC check.
