SPF (Sender Policy Framework)
A DNS record that specifies which mail servers are authorized to send email on behalf of your domain.
SPF (Sender Policy Framework) is an email authentication protocol that helps prevent email spoofing. It works by publishing a DNS TXT record that lists the IP addresses and servers authorized to send email from your domain.
When a receiving server gets an email, it checks the SPF record of the sender's domain. If the sending server's IP matches the SPF record, the email passes authentication.
Example SPF record:
v=spf1 include:_spf.google.com include:sendgrid.net ~all
This record authorizes Google Workspace and SendGrid to send on behalf of the domain.
SPF alone is not enough — it should be combined with DKIM and DMARC for full email authentication. SendSure's Deliverability Testing tool checks all three protocols for any domain.
Related Terms
DKIM (DomainKeys Identified Mail)
A cryptographic email authentication method that verifies an email was sent by an authorized server and wasn't altered in transit.
DMARC (Domain-based Message Authentication)
A protocol that tells receiving servers what to do when SPF or DKIM checks fail for your domain.
Sender Reputation
A score assigned by ISPs to your email sending domain/IP that determines whether your emails reach the inbox.
Related Blog Posts
Want to learn more?
Read our in-depth blog posts on email verification and deliverability.