Free MX Record Lookup
MX Record Lookup
Check the mail servers and priority values for any domain instantly. Diagnose email delivery problems and confirm a mail-provider migration is live.
What is an MX record?
An MX record (Mail Exchange record) is the DNS entry that tells the rest of the internet where to deliver email for your domain. When someone sends a message to you@example.com, their mail server looks up the MX records for example.com to find which hostnames accept mail for that domain. Without a valid MX record, inbound email has nowhere to go and bounces.
Unlike an A record, an MX record does not point to an IP address. It points to a hostname — for example aspmx.l.google.com for Google Workspace or example-com.mail.protection.outlook.com for Microsoft 365 — and that hostname has its own A/AAAA records that resolve to the mail server's actual address.
How to read MX record priority
Every MX record carries a priority value (also called preference). The rule is simple but counter-intuitive: lower numbers are higher priority. A sending server always tries the record with the smallest number first and only falls back to higher numbers if the primary is unreachable.
| Mail server | Priority | What it means |
|---|---|---|
mail1.example.com | 10 | Primary — tried first for every message |
mail2.example.com | 20 | Backup — used only if the primary is down |
alt1.example.com | 30 | Second backup — last resort |
When two MX records share the same priority number, sending servers spread mail between them roughly evenly, which providers use for load balancing. Google Workspace, for instance, publishes several equal-priority hosts so no single server carries all the traffic.
Common email delivery problems MX records cause
- No MX record at all. If a domain has A records but no MX record, some senders fall back to the A record, but many will not — mail silently fails. Every mail-receiving domain needs at least one MX record.
- MX points to a hostname with no A/AAAA record. The MX target must itself resolve to an IP. A typo in the mail-server hostname makes the domain unreachable for email.
- MX pointing at a CNAME or an IP address. Both are invalid per the DNS standard and cause inconsistent delivery. MX targets must be plain hostnames with address records.
- Stale records after a migration. After switching providers, old MX records may still be cached until their TTL expires. Use a DNS propagation checker to confirm the change is live everywhere.
- Missing SPF, DKIM, or DMARC. MX handles inbound mail, but your outbound mail can still be marked as spam if the matching
TXTauthentication records are absent. Check those with the full DNS record lookup.
How to check MX records
The fastest way is the free tool at the top of this page — enter your domain, click Check MX Records, and DNS Dingo queries public DNS-over-HTTPS resolvers and lists every mail server with its priority and TTL. If you prefer the command line:
- nslookup:
nslookup -type=mx example.com - dig (macOS / Linux):
dig MX example.com +short - PowerShell:
Resolve-DnsName example.com -Type MX
For a full walkthrough of these commands see the DNS commands guide.
Need to watch an MX change go live?
MX updates propagate on the same TTL clock as any DNS record. Use the free global checker to see which resolvers have picked up your new mail servers — no signup required.
Check DNS PropagationFrequently Asked Questions
What is an MX record?
An MX record (Mail Exchange record) is a DNS record that tells other mail servers where to deliver email for your domain. Instead of pointing to an IP address directly, an MX record points to a hostname (such as aspmx.l.google.com), which in turn has its own A/AAAA records. Every domain that receives email needs at least one valid MX record.
How do I read MX record priority?
Each MX record has a priority (also called preference) value. A lower number means higher priority, so a mail server with priority 10 is tried before one with priority 20. Sending servers attempt the lowest-numbered host first and fall back to higher numbers if it is unreachable. When two records share the same priority, mail is load-balanced roughly evenly between them.
How do I check the MX records for my domain?
Enter your domain in DNS Dingo's MX record lookup tool above and click Check MX Records. The tool queries public DNS-over-HTTPS resolvers and lists every mail server for the domain along with its priority and TTL. You can also check MX records from a terminal with nslookup -type=mx example.com or dig MX example.com +short.
Why is my domain not receiving email?
The most common causes are a missing or misconfigured MX record, an MX record that points to a hostname with no A/AAAA record, or MX changes that have not finished propagating after a mail-provider migration. Confirm your MX records match exactly what your email provider specifies (Google Workspace, Microsoft 365, etc.), and check that SPF, DKIM, and DMARC TXT records are in place so your mail is not rejected as spam.
Do MX records use IP addresses?
No. An MX record must point to a hostname, never an IP address — that is a requirement of the DNS standard. The hostname it references then needs its own A or AAAA record so sending servers can resolve it to an IP. Pointing an MX record directly at an IP, or at a CNAME, is invalid and can cause silent delivery failures.
How long do MX record changes take to take effect?
MX changes propagate the same way as any DNS record: resolvers keep serving the old value until the record's TTL expires. With a low TTL (300 seconds) most resolvers update within 5 to 15 minutes; with a 3600-second TTL it usually takes 1 to 4 hours, and full global propagation can take up to 24 to 48 hours. Lower your TTL a day before a planned mail migration to speed the cutover.