General
What SPF means
SPF (Sender Policy Framework) is an email authentication protocol designed to detect email spoofing (when a sender’s address is forged) and help ensure that an email message was sent from an authorized mail server. SPF works by allowing a domain owner to specify which IP addresses or mail servers are allowed to send emails on behalf of their domain. This is done by creating a DNS record (Domain Name System) with a list of allowed servers, which receiving mail servers can check when they receive an email from that domain. Learn more: https://en.wikipedia.org/wiki/SPF