SPF Sender Policy Framework

A TXT record in DNS listing the servers allowed to send email in the name of your domain. It starts with v=spf1 and ends with a note on how strictly to take it: -all means turn away, ~all means let through and make a note, ?all means never mind.

There may be exactly one SPF record per domain. Two cancel each other out. Additional senders therefore do not go into a second record. They get taken into the existing one with include:.

SPF only checks the technical sender address, not the name the recipient sees in their mailbox. That is why SPF alone is not enough. It needs DKIM and DMARC alongside it.