Email authentication helps prevent spam. The options below attempt to equip email messages with verifiable information so that the nature of incoming and outgoing messages can be detected automatically.
DKIM DKIM (DomainKeys Identified Mail) is a means of verifying incoming email. It ensures that incoming messages are unmodified and from the sender from whom they claim to be. This feature works to prevent incoming spam messages.
SPF The SPF (Sender Policy Framework) system allows you to specify servers and IP addresses that are authorized to send mail from your domain(s). This feature works to prevent outgoing spam messages.