SPF (Sender Policy Framework)

SPF, or Sender Policy Framework, is an authentication protocol that validates a sender’s identity to inbox service providers (ISPs). SPF records detail all the authorized mail servers that can send emails from a particular domain. SPF authentication provides rules to ISPs so they can recognize whether or not an incoming email message is being sent from an authorized sender. ISPs use these rules to accept, reject, or flag all incoming messages.

As SPF plays a prominent role in determining email deliverability and inboxing rates, remember to have SPF records and other authentication protocols like DMARC, DKIM, and BIMI in place before hitting send.