Source: https://uptimeify.io/resources/platform-and-support/glossary/spf

# SPF (Sender Policy Framework)

> SPF (Sender Policy Framework) is a DNS TXT record that lists which mail servers are allowed to send email on behalf of your domain.

Receiving servers check SPF to detect spoofing: if mail arrives from a server not in your SPF record, it can be rejected or marked as spam. A correct SPF record is one of the three pillars of email authentication, alongside DKIM and DMARC.