How to Set Up DKIM for Mimecast?

DomainKeys Identified Mail (DKIM) is an anti-tamper protocol that ensures security of your emails in transit. It uses digital signatures to check that the email was sent by a specific domain. Before setting up DKIM for Mimecast, you will need to create an outbound definition and an outbound policy. You can then generate a pair of public and private DKIM keys on your Mimecast account. 

1. Setting up a definition on Mimecast.

1. 1. Login to your Mimecast account.
   2. Go to the ‘Administration Console’.
      
      
   3. Navigate to ‘Administration > Gateway > Policies’.
   4. In the ‘Policies’ tab, locate ‘Definitions’ and select ‘DNS Authentication-Outbound’ from the drop-down menu.
   5. To create a new definition, click on ‘New DNS Authentication-Outbound signing’.
   6. Select your Domain name from the lookup box or type your own domain name.
   7. Select the length of the definition. 
   8. Click on ‘Generate’.
   9. After the public key is generated, go to your DNS management console and publish the DKIM key.

2. Setting up a Policy on Mimecast

1. 1. Go to your ‘Administration Console’ on Mimecast.
   2. Go to ‘Administration > Gateway > Policies’.
   3. Click on ‘DNS Authentication-Outbound’.
   4. Search ‘New Policy’ and name it.
   5. Click on ‘Save’.

To verify the successful setup of the new DKIM policy, you can click on ‘Check DNS’ in your Mimecast account. If you see a verified status, it means you have successfully set up DKIM.

Check your DKIM record using EmailAuth’s free DKIM validator tool.