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Glossary

SPF Record (Sender Policy Framework)

An SPF record is a DNS TXT record that specifies which mail servers are authorized to send email on behalf of a domain. Receiving servers check this record to verify that incoming mail comes from a permitted source, helping to prevent email spoofing.

Key Aspects

Domain Authorization

Explicitly lists which IP addresses and servers may send email for your domain.

DNS-Based

Published as a TXT record in your domain's DNS, making it publicly verifiable by any receiving server.

Spam Reduction

Helps receiving servers reject emails from unauthorized sources claiming to be from your domain.

Understanding SPF Records

Sender Policy Framework (SPF) is one of the foundational email authentication protocols. It works by allowing domain owners to publish a list of authorized sending servers in their DNS records. When a receiving server gets an email, it checks the SPF record of the sender's domain to determine whether the sending server is on the authorized list.

An SPF record uses a specific syntax to define authorized senders. For example, "v=spf1 include:_spf.google.com ~all" authorizes Google's mail servers and soft-fails all others. Understanding SPF syntax is important for ensuring third-party services like email signature platforms, marketing tools, and CRM systems can send on your behalf.

Frequently Asked Questions

What does an SPF record look like?
A typical SPF record is a DNS TXT record like: v=spf1 include:_spf.google.com include:sendgrid.net ~all. It lists authorized senders and defines what to do with unauthorized ones.
What is the difference between ~all and -all in SPF?
~all is a soft fail (accept but mark), while -all is a hard fail (reject). Most organizations use ~all during setup and transition to -all once they confirm all legitimate senders are listed.
Can I have multiple SPF records for one domain?
No. A domain should have only one SPF record. Multiple records can cause validation failures. Use the include mechanism to authorize multiple services within a single record.
Do I need to update my SPF record when using Siggly?
Siggly applies signatures within your existing email infrastructure (Google Workspace or Microsoft 365), so no SPF changes are typically needed.

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