The DKIM Check tool will perform a DKIM record test against a domain name and selector for a valid published DKIM key record. DomainKeys Identified Mail (DKIM) defines a domain-level digital signature authentication framework for email by permitting a signing domain to assert responsibility for a message in transit. DKIM authenticates the reputation and identity of the email sender and their email signing practices for additional handling (i.e. does email get delivered, quarantined, or rejected). DKIM authentication of a message is validated via a cryptographic signature and querying the signer’s domain to retrieve a public key. This tool tests the ability to retrieve the DKIM public key using a domain and a selector.

How to Use the DKIM Check Tool: There are two (2) ways to test a DKIM record with the DKIM Record Checker. The first is just using a domain and selector separated by a colon and the second option is using the host/name format of the record.

  • Option 1: (domain):(selector) i.e. mxtoolbox.com:email - where mxtoolbox.com is the domain part and email is the selector, separated by a colon
  • Option 2: (selector).(_domainkey).(domain) i.e. email._domainkey.mxtoolbox.com - where email is the selector followed by ._domainkey. and then mxtoolbox.com as the domain. Note: If you use this method, you will input all of this into the Domain Name input field and leave the Selector field empty.

What is a DKIM Selector? A DKIM selector is text that is added with the domain to create a unique DNS record used during DKIM. This allows multiple keys to exist under one domain which allows for different signatures to be created by different systems, date ranges, or third party services.