Set up SPF and DKIM for Mimecast

To set up SPF and DKIM for Mimecast, please follow the steps given below:


If you don’t have SPF record and wants to set the SPF record for Mimecast then :

  • Log in to your DNS management console
  • Navigate to your domain section and publish the following SPF record: 

            v=spf1 ~all

If you already have SPF record and wants to add the Mimecast domain into existing SPF record then:

  • Log in to your Domain Registrar
  • Modify your domain’s SPF record to specify Mimecast as the authorized outbound service

For Example:

If your previous SPF record was 

          v=spf1 ~all 

your new SPF record will be 

          v=spf1 ~all


  • Login to Mimecast.
  • Select Administration console.
  • From the top left select Administration > Gateway > policies.
  • Select definitions drop down select DNS Authentication – Outbound.
  • Select New DNS Authentication – Outbound signing.
  • Set a name for the definition
  • Tick the checkbox Sign outbound mail with DKIM
  • Use the lookup option to select domain to DKIM sign
  • Select generate
  • Create a TXT record within your DNS with the public key provided save and exit
  • Verify public key in Mimecast console