The Sender Policy Framework (SPF) is an email authentication, which is a part of the DooxMail Diagnostic tool that is used to prevent cyber attacks wherein spammers might send messages on behalf of your domain name.

The DooxMail SPF Check feature enables domain owners to publish an SPF record in the DNS that specifies which mail servers they use to send an email. During SPF email authentication an SPF check is done to verify that the domain in the "from" address in the email header matches a valid IPaddress in the SPF record. If the addresses do not match, the SPF test fails and the email can be
rejected by the email receiver.