What Is an MX Lookup?
MX Lookup shows you the mail servers that handle email for any domain. MX records tell the internet where to deliver email sent to that domain.
How Does It Work?
The tool queries DNS servers specifically for MX records. Each MX record has two parts: a priority number and a mail server name.
- Priority - A number that decides which mail server gets email first. Lower numbers get higher priority.
- Mail Server - The name of the server that receives email for the domain.
Why Use MX Lookup?
- Make sure your domain can receive email
- Fix email delivery problems
- Confirm your mail server is set up correctly
- Check that email points to the right provider after a switch
- See what email setup another domain uses
Understanding MX Priority
The lower the priority number, the more important the server. For example:
- Priority 10 - Main mail server. Gets email first.
- Priority 20 - Backup server. Used when the main server is down.
- Priority 30 - Another backup. Used if both above are unavailable.
If two servers share the same priority, email is split between them for balance.
How to Use This Tool
Type a domain like example.com into the box and click Lookup. You will see all MX records with their priority values and server names.
Common MX Setups
- One MX Record - Simple setup for small sites with a single mail server.
- Multiple Records, Different Priorities - Gives you a backup if the main server fails.
- Multiple Records, Same Priority - Splits email load across several servers.
Common Problems
- No MX Records - Email may fall back to the A record, but this is not reliable.
- IP Address as Target - MX records must point to a server name, not an IP. Using an IP will break email delivery.
- Missing Reverse DNS - Mail servers without reverse DNS may have their emails marked as spam.
Frequently Asked Questions
Can a domain have multiple MX records?
Yes. Most domains have at least two: a primary and a backup. This keeps email flowing even if one server goes down.
What happens if the main MX server is down?
Email is automatically sent to the next server in the priority list.
Do MX records control outgoing email?
No. MX records only affect incoming email. Outgoing email depends on your mail server settings.
How do I know if my MX records are right?
Run an MX lookup and compare the results with the settings your email provider gave you.
What is the difference between MX and A records?
A records point a domain to an IP address for web traffic. MX records point to mail servers for incoming email.
Can I use an IP address as an MX target?
No. The DNS standard requires MX records to point to a hostname. Using an IP address will cause email to fail.