In short. An MX record in DNS says which server accepts mail for a domain. You need to check it when mail isn't arriving, when setting up email, or when diagnosing deliverability. It's read in seconds: enter the domain in a DNS check and look at the MX field — there you'll see the mail servers' addresses with priority numbers (lower number = higher priority). If there are no MX records at all, the domain accepts no mail and any address on it is undeliverable. Below is how to check MX, what the priorities mean, and which problems come up most often.
What an MX record is and why to check it
MX (Mail Exchanger) is a type of DNS record that answers the question "where to deliver mail for this domain." When someone writes to you@example.com, the sending server looks at the MX record of example.com and learns the address of the recipient's mail server. Without a correct MX, mail simply can't find where to go.
An MX record is a pointer to the domain's post office. With a pointer, letters know where to go; missing or pointing to the wrong place, mail bounces or vanishes.
It's worth checking MX in three cases: mail isn't arriving, you're setting up or moving email, or you're diagnosing why mail goes to spam or doesn't arrive.
How to check in a minute
Method 1 — without a terminal. Enter the domain in a DNS check and look at the MX-type records: it shows the mail servers' addresses and their priorities.
Method 2 — a command:
dig +short MX example.com
# sample answer:
# 10 mx.example-mail.net.
# 20 mx-backup.example-mail.net.
# the number on the left = priority (lower = higher)
# or via nslookup:
nslookup -type=mx example.comMethod 3 — check the rest of the mail setup. MX is only about receiving. So your mail isn't treated as forged and does arrive, you also need SPF, DKIM, and DMARC — an email-setup check checks those together with MX.
What the result means
| What you see | What it means |
|---|---|
| One MX with a server address | The domain accepts mail through this server — normal |
| Several MX with different numbers | Primary and backup servers; the lower number is higher priority |
| Empty / no MX | The domain accepts no mail — every address on it is undeliverable |
| MX points to a foreign/old host | Mail goes to the wrong place — a common cause of "letters vanish" |
Priority is an order, not a quality: the sending server first tries the MX with the lowest number, and if it's unavailable, the next one up. That's how a backup mail server works.
Common problems
- No MX record. The domain is for the site only, mail was never set up — you can't write to it. If mail is needed, add your mail provider's MX.
- MX points to an old server. After moving mail, the MX wasn't updated — letters go to the previous host. Check that the MX matches the current provider.
- Changed but not applied. After editing, MX doesn't update instantly — until the TTL expires, the old value lives in caches. Give it time and recheck.
- MX exists, but mail still goes to spam. Receiving is set up, but the problem is send-side authentication — check SPF, DKIM, and DMARC.
Frequently asked questions
Can a site exist without an MX record?
Yes. MX is only needed to receive mail on a domain. If the domain is used solely for the site, with mail on another domain or not needed at all, there may be no MX record, and that's normal. The site still works — that's handled by A/AAAA records, not MX.
How many MX records should there be?
One is enough. Several are added for resilience: a primary server with a lower priority and a backup with a higher one. Many MX records for no reason aren't needed — they complicate diagnosis.
I checked MX — it's correct, but mail doesn't arrive. Why?
MX is only about where to deliver incoming mail. If receiving is set up and mail is still lost or goes to spam, the cause is usually elsewhere: sender authentication (SPF/DKIM/DMARC), reputation, or a blacklist. How to check whether the recipient address exists is in the article on email verification, and setting up the records is in the MX guide.
Checklist to remember
- An MX record says which server accepts mail for the domain.
- Check in seconds: a DNS check or
dig +short MX domain. - The number on the left is priority: lower = higher; several MX = primary + backup.
- No MX — the domain accepts no mail; MX to an old host — mail goes to the wrong place.
- MX correct but mail in spam — the problem is SPF/DKIM/DMARC, not receiving.