SPF Basics

Foundational guides to understanding Sender Policy Framework.

How SPF Works: The Complete Authentication Flow Explained

Understand how SPF email authentication works, from DNS lookups to pass/fail results. Learn about mechanisms, qualifiers, and more.

The SPF "a" Mechanism Explained

Learn how the SPF "a" mechanism works, when to use it, its syntax with and without a domain argument, and how it compares to the "mx" mechanism.

SPF "all" Mechanism: Softfail vs Hardfail Explained

Understand the SPF all mechanism and its qualifiers: +all, -all, ~all, and ?all. Learn the difference between softfail and hardfail.

SPF FAQ: Frequently Asked Questions About SPF Records

Answers to common SPF questions: multiple records, propagation time, DNS lookups, combining includes, and more. Get your SPF questions answered.

SPF Record Examples: Real-World Records for Every Scenario

Practical SPF record examples for common setups including Google Workspace, Microsoft 365, SendGrid, and multi-provider configurations.

SPF Record Syntax: A Complete Reference Guide

Learn every SPF record syntax element including mechanisms, qualifiers, and modifiers. A plain-English guide with examples.

What is SPF? A Plain-English Guide

Learn what SPF (Sender Policy Framework) is, why it matters for email deliverability, and how it helps prevent email spoofing. No technical jargon required.