Glossary · Marketing, CRM & Growth
SPF
Overview
What SPF is
SPF, or Sender Policy Framework, is an email authentication standard that helps prevent forgery of the sending domain. A domain owner publishes an SPF record—a specially formatted DNS TXT record—that lists the mail servers and IP addresses allowed to send email on the domain's behalf. Receiving servers check that list to judge whether a message is legitimate.
How SPF works
When an email arrives, the receiving server reads the return-path (envelope sender) domain, looks up its SPF record in DNS, and compares the sending server's IP against the authorized list. The check returns a result such as pass, fail, or softfail. Mailbox providers use that outcome, alongside other signals, to decide whether to deliver, flag, or reject the message.
Why it matters for your business
SPF is one leg of the email authentication trio—SPF, DKIM, and DMARC—that underpins deliverability. Without it, legitimate messages are more likely to land in spam and your domain is easier to spoof. As part of email marketing and deliverability work, a team configures SPF correctly, avoids the common "too many DNS lookups" error, and keeps it aligned with DKIM and DMARC.
Where we use it
Related Zen in Tech services
How our team puts SPF to work in real projects.
FAQ
SPF — common questions
What does SPF do?
SPF specifies which mail servers are authorized to send email for your domain, so receiving servers can detect and reject spoofed messages that claim to come from you. It's a core defense against email forgery and a factor in deliverability.
SPF vs DKIM vs DMARC?
SPF authorizes sending servers, DKIM cryptographically signs messages to prove they weren't altered, and DMARC ties the two together with a policy for handling failures plus reporting. They work best deployed together, not as alternatives.
Do I need SPF?
Yes. Any domain that sends email should publish an SPF record. It's required in practice for good deliverability, and major providers like Google and Yahoo expect proper authentication from bulk senders.
Need SPF done right?
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