How to Check MX Records: A Step-by-Step Guide

Checking MX records is the first step in troubleshooting email delivery problems. Whether you're setting up a new domain, switching email providers, or diagnosing why emails aren't arriving, an MX lookup shows you exactly how email routing is configured.

This guide walks you through checking MX records and understanding what the results mean.

Check MX Records Now

Enter any domain to see its mail server configuration:

Why Check MX Records?

There are several situations where checking MX records is essential:

Setting up email for a new domain. Before email can work, MX records must point to your email provider's servers. Checking confirms they're configured correctly.

Switching email providers. When moving from one provider to another, you need to update MX records. Checking verifies the old records are removed and new ones are in place.

Troubleshooting delivery problems. If emails aren't arriving, incorrect MX records are a common cause. Checking reveals misconfiguration.

Verifying a client's setup. Agencies and IT consultants often need to audit email configuration for clients. MX lookups provide quick visibility.

Investigating suspicious email. Checking a sender's domain MX records can reveal whether it's a legitimate organization or a potential phishing attempt.

Reading MX Lookup Results

When you check a domain's MX records, you'll see several pieces of information:

Priority value. A number indicating the order servers should be tried. Lower numbers mean higher priority. Mail servers attempt delivery to the lowest-priority server first.

Mail server hostname. The fully qualified domain name of the server that accepts email. This should be a legitimate mail server, not a random hostname.

Server status. Whether the mail server is responding to connections. A server might be listed in DNS but not actually accepting email.

Here's an example of typical results:

These results show two mail servers with proper redundancy. The primary (priority 10) handles most traffic, with a backup (priority 20) available if needed.

What to Look For

When reviewing MX lookup results, check these things:

At least one MX record exists. Domains without MX records can't receive email. If the lookup returns no results, email to that domain will bounce.

Hostnames are correct. If you're using Google Workspace, you should see Google's servers. For Microsoft 365, you should see Microsoft's servers. Unfamiliar hostnames might indicate misconfiguration or that records haven't been updated after a provider switch.

Priorities make sense. You should see a primary server with the lowest priority number and backup servers with higher numbers. If all priorities are the same, that's intentional load balancing.

Servers are responding. A hostname in DNS that doesn't respond indicates either a server problem or incorrect configuration.

Common MX Record Patterns

Different email providers have recognizable MX patterns:

Google Workspace:

• aspmx.l.google.com (priority 1)
• alt1.aspmx.l.google.com (priority 5)
• Additional alt servers at priorities 5 and 10

Microsoft 365:

• yourdomain-com.mail.protection.outlook.com
• Single MX record is normal for Microsoft

Self-hosted email:

• Usually mail.yourdomain.com or similar
• Often includes a backup server

Email forwarding services:

• Various hostnames depending on the service (Improvmx, ForwardEmail, etc.)

If you're expecting one provider but seeing another's servers, your MX records may not have been updated after a switch.

Troubleshooting Common Issues

MX lookups help diagnose these frequent problems:

No MX Records Found

The domain has no MX records configured. Email sent to this domain will bounce with errors like "no mail exchanger" or "domain not configured for email."

Solution: Add MX records pointing to your email provider's mail servers.

Wrong Mail Servers Listed

The MX records point to servers from a previous email provider or an incorrect configuration.

Solution: Update MX records to point to your current email provider. Remove any outdated records.

Mail Server Not Responding

The MX record exists and points to a valid hostname, but the server isn't accepting connections.

Possible causes:

• Server is down or misconfigured
• Firewall blocking port 25
• DNS is correct but the server doesn't handle mail for this domain

Solution: Check that the mail server is running and accepting connections on port 25. Verify the server is configured to accept mail for your domain.

Multiple Conflicting Records

Old and new MX records exist simultaneously, potentially routing some email to the wrong place.

Solution: Remove outdated MX records, keeping only the records for your current email provider.

Only One MX Record

Having a single MX record means no failover if that server goes down.

Solution: Add backup MX records if your email provider supports them. Most major providers like Google and Microsoft have multiple servers for redundancy.

Checking MX Records with Command Line Tools

Besides web-based tools, you can check MX records using command line utilities:

nslookup (Windows):

nslookup -type=mx example.com

dig (macOS/Linux):

dig mx example.com

host (Linux):

host -t mx example.com

These commands query DNS directly and return raw results. They're useful for technical troubleshooting but require more expertise to interpret than a dedicated lookup tool.

When to Check MX Records

Make MX lookups part of your routine email maintenance:

After any DNS changes. Verify MX records weren't accidentally modified or deleted.

Before and after email migrations. Confirm the switch happened correctly.

When troubleshooting delivery. Start with MX records before investigating other causes.

Periodically for monitored domains. Catch unauthorized changes or accidental deletions.

When onboarding new clients. Understand their current email configuration before making changes.

Beyond Manual Checks

Checking MX records manually works for one-time verification, but ongoing monitoring catches issues faster. DNS records can change unexpectedly due to:

• Accidental modifications during other DNS work
• Domain renewal issues affecting DNS
• Unauthorized access to DNS management
• Provider-side changes or migrations

Automated monitoring checks your MX records regularly and alerts you when something changes, often before you notice email problems.

Monitor Your MX Records

Checking once is good. Monitoring continuously is better. The Email Deliverability Suite watches your SPF, DKIM, DMARC, and MX records daily and alerts you when something breaks.