Servers and priority
The sender first tries the server with the lowest priority number, then the others if it is unavailable. An MX record must name a server with an A or AAAA address record, rather than an IP address or CNAME alias.
MX lookup: a domain’s mail servers
An MX record names the servers that receive mail for a domain. We list them by priority, check that each has an address and reverse DNS, and connect on port 25 to see whether the server encrypts the connection.
Find a domain’s mail servers
You can paste a whole email address: we take the part after @.
What the MX lookup shows
Reverse DNS
The server address needs a PTR record whose name points back to the same address. Without it, mail from the server is often treated as spam.
Encryption
We connect to the first two servers on port 25 and see whether they offer STARTTLS and whether the certificate is valid.
MX record questions
Priority, a backup server and switching mail providers.
What does the priority in an MX record mean?
The number before the server name: the lower it is, the sooner a sender tries that server. Servers with equal numbers share mail evenly; higher ones receive mail only when the first are unreachable. The value itself doesn’t matter, only the order: 10 and 20 work the same as 1 and 5.
Do I need a backup mail server?
One reliable mail server is usually enough for a small domain. If it is temporarily unavailable, senders normally queue messages and retry for several days. After that period, an undelivered message is returned to its sender with an error. A backup server helps when delays are critical; it needs the same spam protection as the primary server.
How do I move mail to another provider without losing messages?
Create the mailboxes at the new provider first and copy old mail there, then change the MX records. While the change propagates, usually from a few minutes to a day, some mail still reaches the old server, so don’t delete it right away and keep collecting mail from it for a few days. Remember to update SPF and DKIM for the new provider: the check shows if anything from the old one is left.
More tools: Domain email
Email settings checker
MX, SPF, DKIM, DMARC and blacklists in one go, scored out of nine.
OpenSPF checker
Check an SPF record for errors, the DNS lookup limit and sender rules.
OpenDKIM checker
Find a DKIM key in DNS and check its length and status.
OpenDMARC checker
Whether there is a record, which policy it sets and where reports go.
OpenBlacklist check
Check an IPv4 address or a domain’s mail server IPs against blacklists.
OpenSPF generator
Choose your mail senders to create an SPF record for DNS.
OpenDMARC generator
Choose how to handle messages and where to send DMARC reports.
OpenEmail on your own domain comes with hosting
On our hosting, mailboxes on your domain are part of the plan, and mail records are set up in the Plesk panel.
Keep domain records on reliable DNS
Host MX, SPF, DKIM and DMARC on our name servers: you edit records yourself at any time, the domain can stay with any registrar and mail with any provider.