How SPF Works

The core idea

SPF is an email authentication method published through DNS. It helps receiving mail systems check whether a sending server is authorized for the claimed domain.

Google Workspace explains SPF as a DNS TXT record that lists the servers allowed to send mail for your domain.

A domain owner publishes an SPF record in DNS. When email is received, the receiving server checks whether the sending server matches what the SPF record allows.

This helps reduce some forms of spoofing and misidentified mail.

How it works step by step

A domain owner publishes an SPF record in DNS. When email is received, the receiving server checks whether the sending server matches what the SPF record allows.

This helps reduce some forms of spoofing and misidentified mail.

SPF matters because email spoofing and domain impersonation are common problems.

It is one of the core technologies used in modern email authentication alongside DKIM and DMARC.

What affects the outcome

SPF matters because email spoofing and domain impersonation are common problems.

It is one of the core technologies used in modern email authentication alongside DKIM and DMARC.

A common misconception is that SPF alone solves all email spoofing problems. In reality, it is only one part of a larger email authentication setup.

Another misconception is that SPF works independently of the rest of email delivery behavior. In practice, alignment and other checks still matter.

Where people run into it

A common misconception is that SPF alone solves all email spoofing problems. In reality, it is only one part of a larger email authentication setup.

Another misconception is that SPF works independently of the rest of email delivery behavior. In practice, alignment and other checks still matter.

Related questions

What to learn next

Sources

• Google Workspace: Set up SPF
• Google Email Sender Guidelines