What Is SPF? A Simple Guide to Sender Policy Framework

Learn what SPF means, how SPF records work, and why SPF matters for email deliverability.

SPF stands for Sender Policy Framework. It is an email authentication standard that tells receiving mail servers which platforms are allowed to send email for your domain. If your business uses a bulk email tool, your SPF record helps Gmail, Outlook and other mailbox providers understand whether that tool is authorised.

This guide is part of the Inbox Health learn hub. For the wider picture, see our guide to email authentication and our explanation of email deliverability.

Why SPF matters for SMEs

For SMEs, SPF matters because email is often directly connected to revenue. Campaigns promote offers, nurture leads, recover abandoned baskets and keep customers informed. If mailbox providers distrust your setup, performance can fall even when your marketing message is good.

How SPF affects bulk email

Bulk email platforms make sending easier, but they do not remove responsibility for trust. Your domain, sending configuration, subscriber list and engagement history all contribute to how your campaigns are treated. A poorly configured setup can make a legitimate business look risky.

Common SPF problems

The most common issues include missing records, weak alignment, old lists, high bounce rates, low engagement and sending from domains that have not built enough trust. Many businesses only discover the problem after open rates drop or recipients report that emails are landing in junk.

• Missing or incomplete setup
• Poor alignment between tools and domains
• High bounce rates or weak list hygiene
• Low engagement from subscribers
• Sudden changes in sending volume or behaviour

How to improve SPF

The best approach is to diagnose before changing everything. Start by checking authentication, then review reputation, list hygiene and engagement. Fix the highest-risk issues first rather than relying on guesswork or repeatedly changing campaign content.

Related terms

Deliverability rarely depends on one factor. It is worth also understanding What Is DKIM? A Simple Guide for Business Email, What Is DMARC? A Simple Guide, What Is Sender Reputation?.

Frequently asked questions