MX Record Lookup

Check mail exchange records, verify email server configuration, and analyze routing priorities for any domain.

Real-time DNS LookupPriority AnalysisProvider Detection

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What is an MX Record?

An MX (Mail Exchange) record is a DNS resource record that specifies the mail servers responsible for accepting email messages on behalf of a domain [^44^][^50^]. Think of it as a postal sorting system for the internet—when someone sends an email to your domain, MX records tell sending servers exactly where to deliver that message.

MX records are essential for email routing via SMTP (Simple Mail Transfer Protocol). Without properly configured MX records, email servers wouldn't know where to deliver messages, resulting in bounced emails or delivery failures [^49^][^51^].

Priority System

Lower numbers indicate higher priority. A server with priority 10 is tried before priority 20 [^45^][^52^].

Priority 10 → Primary (First)

Priority 20 → Secondary (Backup)

Priority 30 → Tertiary (Failover)

Failover & Load Balancing

Multiple MX records provide redundancy. If the primary server is down, email automatically routes to the next priority server [^44^][^47^].

✓ High availability

✓ Automatic failover

✓ Load distribution

Common Email Provider Setups

Google Workspace (Gmail)

Priority	Mail Server
10	aspmx.l.google.com
20	alt1.aspmx.l.google.com
30	alt2.aspmx.l.google.com
40	alt3.aspmx.l.google.com
50	alt4.aspmx.l.google.com

Microsoft 365 (Outlook)

Priority	Mail Server
0	yourdomain-com.mail.protection.outlook.com

* Replace "yourdomain-com" with your actual domain (hyphens instead of dots)

MX Record Essentials

!Critical Requirements

•MX records must point to hostnames (A/AAAA records), never IP addresses [^45^][^55^]
•Cannot point to CNAME records (RFC violation) [^44^][^49^]
•Target host must resolve via A or AAAA record [^55^]

?Troubleshooting Tips

•Priority 0 is highest priority (tried first) [^46^]
•Multiple servers with same priority = load balancing [^51^]
•TTL values affect how quickly changes propagate [^56^]

Frequently Asked Questions

What is an MX record?

An MX (Mail Exchange) record is a DNS record that directs email messages to mail servers. It specifies which servers are responsible for receiving email on behalf of a domain and in what priority order. MX records are essential for email delivery and include a priority value (lower numbers = higher priority) and the hostname of the mail server.

How do MX record priorities work?

MX records use priority values (0-65535) where lower numbers indicate higher priority. When sending email, mail servers try the lowest priority number first. If that server is unavailable, they move to the next higher number. For example, a server with priority 10 is tried before priority 20. Multiple servers can share the same priority for load balancing.

What happens if there is no MX record for a domain?

If no MX record exists, email servers will attempt delivery to the domain's A or AAAA record (the root domain IP). However, this is not recommended and often leads to email delivery failures or messages being rejected. Proper MX records are required for reliable email delivery.

Can MX records point to an IP address?

No, MX records must point to a fully qualified domain name (FQDN) like mail.example.com, not an IP address. The hostname must have its own A or AAAA record that resolves to an IP address. This requirement is defined in RFC standards and ensures proper email routing.

What are common MX record configurations for email providers?

Google Workspace uses multiple MX records: aspmx.l.google.com (priority 10), alt1.aspmx.l.google.com (priority 20), and alt2-4 (priorities 30-50). Microsoft 365 typically uses: yourdomain-com.mail.protection.outlook.com (priority 0 or 10). Most providers supply multiple records for redundancy and failover.