Email authentication is the effort to equip messages of the email transport system with enough verifiable information, so that recipients can recognize the nature of each incoming message automatically. Enabling email authentication will help fight the spread of spam.
Both of the provided methods work to prevent forged mail from going in and out of the server. The great benefit of enabling these methods is to prevent mail from looking like it is coming from your domain(s). When enabled, these methods should reduce the amount of bounced messages or unwanted emails received when spammers "spoof" one or more of your email addresses.
DomainKeys is an e-mail authentication system that allows for incoming mail to be checked against the server it was sent from to verify that the mail has not been modified. This ensures that messages are actually coming from the listed sender and allows abusive messages to be tracked with more ease.
DomainKeys is only effective if enabled on the authoritative DNS server for the zone.
SPF will specify which machines are authorized to send email from your domain(s). This means that only mail sent through this server will appear as valid mail from your domain(s) when the SPF records are checked.
SPF is only effective if enabled on the authoritative DNS server for the zone and if both the sending and receiving mail servers have SPF enabled.
Both the solutions can be enabled by clicking on the Enable buttons besides their descriptions.
The Disable buttons disable them.
The Advanced Settings section allows additional configurations to be defined.
The user can add Hosts, MX records and IP blocks that will be approved for sending e-mail.
Also SPF settings for additionally included domains can be added to the current SPF settings.
Click on the Update button to confirm the new setup.