By using txt or spf records the owner of a domain name is able to specify which machines are allowed to send emails using their domain. This article describes how to update a domain name service dns record so that you can use sender policy framework spf with your custom domain in office 365. How To Set Up Spf And Dkim With Postfix On Ubuntu Server In all cases customers with existing spf records should review their entries to ensure mimecast servers are referenced exactly once.
