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Email Marketing Glossary.

Clear, no-fluff definitions of every email marketing term that matters—from open rates to double opt-in. 

 

SPF

SPF (Sender Policy Framework) is an email authentication standard that lists which mail servers are allowed to send email on behalf of your domain, helping prevent spoofing.

Also known as: Sender Policy Framework

SPF is one of the three pillars of email authentication, alongside DKIM and DMARC. It's how you tell the world's mailbox providers which servers are legitimately allowed to send email using your domain.

How does SPF work?

You publish an SPF record in your domain's DNS listing the approved sending servers. When you send, the receiving server checks that record. If the sending server isn't listed, the email can be flagged or rejected.

Why does SPF matter?

Without SPF, spammers can more easily spoof your domain, and mailbox providers are more likely to distrust your mail. It's a baseline requirement for good deliverability in 2026.

SPF, DKIM, and DMARC

SPF verifies the sending server, DKIM adds a tamper-proof signature, and DMARC ties them together and tells providers what to do on failure. You need all three for full protection.

Related terms

Email Deliverability Sender Reputation DKIM DMARC Hard Bounce

Related reading from Drip

Ecommerce Email Deliverability: 9 Ways to Reach the Inbox Email Setup (Help Center)

Frequently asked questions

What does SPF stand for?
SPF stands for Sender Policy Framework. It's an email authentication protocol that specifies, via a DNS record, which mail servers are authorized to send email on behalf of your domain.
How does SPF work?
You publish an SPF record in your domain's DNS listing approved sending servers. Receiving mail servers check that record against the actual sender; if it isn't authorized, the message can be flagged or rejected.
Why is SPF important for deliverability?
SPF helps prevent spammers from spoofing your domain and signals to mailbox providers that your mail is legitimate. Missing or misconfigured SPF can send your emails to spam.
Is SPF enough on its own?
No. SPF should be used together with DKIM and DMARC. SPF authorizes sending servers, DKIM adds a cryptographic signature, and DMARC enforces policy and reporting. All three are needed for full authentication.
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