Sender Policy Framework — an email authentication protocol that allows domain owners to specify which mail servers are authorized to send email on behalf of their domain, helping receiving servers detect forged sender addresses.
Sender Policy Framework — an email authentication protocol that allows domain owners to specify which mail servers are authorized to send email on behalf of their domain, helping receiving servers detect forged sender addresses.
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SPF is one of the foundational email authentication protocols. It works by allowing domain owners to publish a list of authorized mail servers in their DNS records. When a receiving mail server gets an email, it checks whether the sending server's IP address is on the authorized list.
Without SPF, anyone can send an email that appears to come from any domain. SPF closes this gap by providing a way to verify that the server sending the email is actually authorized by the domain owner. It's the first line of defense against email spoofing.
SPF has limitations — it only checks the envelope "from" address (Return-Path), not the header "From" address that users see. This is why SPF alone is insufficient and should be combined with DKIM and DMARC for complete protection.
When IsThisAScam analyzes an email, SPF verification is one of the first checks performed. If an email claims to be from "bankofamerica.com" but was sent from a server not listed in Bank of America's SPF record, this is flagged as a strong indicator of spoofing.