Email authentication

What is SPF?

A plain-language guide to the systems allowed to send for a domain.

What it does

SPF is a DNS record that lists authorized sending infrastructure. Receiving systems can compare the server delivering a message with that published list.

What it does not do alone

SPF does not by itself protect the visible From address in every forwarding scenario. DMARC adds alignment and policy, while DKIM provides another authentication path.

SPF records also have technical limits, so adding every service without reviewing the final record can create failures.