whatsmydns.net - DNS Propagation Checker
Waiting for lookup request...

MX Record Lookup

whatsmydns.net MX Lookup tool lets you query DNS servers and get instant results.

Mail Exchanger or MX lookups are used to determine the MX records associated with a domain.

Looking for easier to understand results? Use the Global DNS Checker tool.

DNS MX Record

MX records, known as Mail Exchanger records are used to identifiy which server should be used when sending emails to an address at the domain that the records are for.

Example MX record

An example MX record may look like the following:

Record Type Priority Value TTL
example.com MX 10 mail1.example.com 3600

example.com represents the domain of the record.

MX is the record type.

10 is the priority of the record. The lower the value, the higher the priority.

mail1.example.com is the value of the record. This is the address of the server which should handle email for this domain.

3600 is the TTL (time to live) of the record in seconds, this example represents 1 hour. This means that when a record has had updates made to it, then it will take 1 hour to update.

Multiple MX records

In many cases multiple MX records are added to a domain name, this allows for primary and secondary (backup) mail servers as well as a form of load balancing.

Lower priority records are always tried first when attempting to deliver mail. In the case that the mail server specified in the record with the lower value returns an error when attemping to deliver mail, the next highest priority MX record will be used. If multiple records have the same priority, then one will be chosen at random as a means to spread the load over multiple email servers.

Backup MX records

Backup MX records allow you to set a priority of which mail server should try and process the email first.

The lower the value, the higher the priority.

Record Type Priority Value TTL
example.com MX 10 mail1.example.com 3600
example.com MX 20 mail2.example.com 3600

In this example, the mail server at mail1.example.com will try to handle processing the email first.

Load balanced MX records

Multiple MX records with the same priority value allow you to have multiple mail servers processing email where one is picked at random. This is useful for spreading the load across many servers or network devices where a single server may not have the capacity to handle all emails at once.

Record Type Priority Value TTL
example.com MX 10 mail1.example.com 3600
example.com MX 10 mail2.example.com 3600

In this example, one of the two mail servers will get a chance to handle processing the emails equally.

Load balanced and backup MX records

A combination of backup and load balanced email servers can also be achieved with additional MX records.

Record Type Priority Value TTL
example.com MX 10 mail1.example.com 3600
example.com MX 10 mail2.example.com 3600
example.com MX 20 mail3.example.com 3600

In this example, the mail servers mail1.example.com and mail2.example.com will get a chance to handle processing the emails equally. If they fail to respond then the mail server at mail3.example.com will try to handle processing the email.