Networking · Security
SPF
Also known as: Sender Policy Framework
A DNS record listing which servers are authorized to send email for your domain — receiving servers check it to block impersonation.
SPF — Sender Policy Framework — is a DNS record that specifies which mail servers are authorized to send email on behalf of your domain. When a receiving mail server gets a message claiming to be from you, it checks your SPF record to verify the sending server is on your approved list.
SPF prevents a basic form of email spoofing: unauthorized servers impersonating your domain. Publishing an SPF record is a prerequisite for DMARC enforcement and a baseline expectation for email deliverability.
The operational issue: every service that sends email on your behalf — your CRM, your marketing platform, your ticketing system, your HR software — needs to be listed in your SPF record. Organizations that add SaaS tools over time frequently forget to update their SPF record, which causes legitimate email to fail authentication and land in spam.
SPF validates the sending server, not the message itself. It also doesn't protect the "From" address the recipient sees in their email client. Those gaps are filled by DKIM and DMARC respectively.