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MX Lookup

Run a free MX lookup to see which mail servers receive email for any domain, their priority and IP addresses, and the email provider behind them.

Examples:

What is an MX record?

An MX (mail exchanger) record is a DNS record that tells other mail servers where to deliver email for your domain. Each record has a priority and a hostname. Senders try the lowest number first and move to the next one only if it doesn't respond.

MX records control incoming mail only. Whether your outgoing email reaches the inbox depends on your SPF, DKIM and DMARC records and your sender reputation.

MX records for Google Workspace and Microsoft 365

The values each provider tells you to publish

Google Workspace

Priority1Valuesmtp.google.com

Domains set up before 2023 may use five records starting with aspmx.l.google.com. Google still supports them.

Microsoft 365

PriorityLowest, for example 1Value<MX token>.mail.protection.outlook.com

Find your MX token in the Microsoft 365 admin center under Domains. Microsoft recommends a single MX record.

Common MX record errors

No MX record

Without an MX record the domain can't receive email, so replies bounce. Many receivers also treat mail from domains that can't accept replies as suspicious.

MX pointing to an IP address

MX records must name a hostname. Point the record to a hostname with an A record, such as mail.yourdomain.com, instead of the IP itself.

MX pointing to a CNAME

The MX target should resolve directly to A or AAAA records. Some mail servers refuse to deliver to a CNAME, so use the final hostname.

Leftover records from an old provider

After a migration, old MX records with the same or a lower priority keep catching some mail. Remove every record for the system you left.

MX Lookup: Common Questions

Everything you need to know about MX records

An MX lookup is a DNS query that returns the mail exchanger records for a domain: the servers that accept email sent to it, each with a priority number. This MX lookup tool also resolves each server's IP addresses, shows which email provider the domain uses, and flags setup errors that could make incoming mail bounce.

Enter your domain in the MX lookup above and run it. You'll see every MX record with its priority, mail server and IP addresses. You can also check from a terminal with nslookup -type=mx yourdomain.com on Windows, or dig mx yourdomain.com on macOS and Linux.

Google Workspace uses a single MX record today: smtp.google.com with priority 1. Domains set up before 2023 often have five older records starting with aspmx.l.google.com and alt1 to alt4. Google says those older values are still supported, so you only need to change them if you want the simpler setup.

Yes, a domain can have several MX records. Senders try the lowest priority number first and fall back to higher numbers if it doesn't answer. Multiple records are normal for backup servers, but every record should point to the same mail system. Mixing providers sends some messages to the wrong place.

MX changes usually take effect within an hour, but they can take up to 48 hours to reach every DNS resolver. The deciding factor is the TTL of the old record. Before a planned migration, lower the TTL to five minutes a day ahead, so the switch happens quickly once you update the record.

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