What Is SPF And Can It Help With Email Deliverability?

SPF: The OG Foundation of Email Authentication

SPF (Sender Policy Framework) is an email authentication protocol designed to stop cybercriminals from pretending to send emails from your domain. In short, it helps email servers tell the difference between you and an imposter.

SPF works by publishing a public record (a sort of “approved senders list”) in your domain’s DNS. This record tells receiving mail servers which servers are allowed to send emails on your behalf. Anyone can look it up, and email servers do so automatically to decide whether a message claiming to be from you is legitimate.

What SPF Actually Means

SPF stands for Sender Policy Framework. But in its early days (the early 2000s), it was called Sender Permitted From. Thankfully, the name got a professional upgrade in 2004.

At its core, SPF allows domain owners to specify which email servers are authorised to send messages from their domain. It’s like giving bouncers a guest list. If a server’s not on the list, its emails shouldn’t be trusted.

How SPF Works — Step by Step

Publish your SPF record.
The domain owner creates an SPF record and adds it to the DNS. This record lists all IP addresses or hostnames permitted to send emails from the domain.
Email is sent.
When someone sends an email using your domain, the recipient’s server extracts the sender’s domain name from the email header.
SPF lookup.
The recipient’s mail server performs a DNS lookup to retrieve your SPF record and check if the sending server is authorised.
Decision time.
If the server is on your SPF list, the email is accepted. If not, the receiving server may flag it as spam or reject it entirely.

It’s a simple but powerful system for reducing email forgery.

How to Use SPF

To start using SPF, you’ll need to:

Understand how SPF works (you’re halfway there already).
Check whether your email service provider supports SPF.
Create and publish an SPF record in your domain’s DNS.

For best results, combine SPF with DKIM (DomainKeys Identified Mail) and DMARC (Domain-based Message Authentication, Reporting & Conformance). Together, these form the holy trinity of modern email authentication.

Why SPF Matters

SPF does more than keep your IT team happy. It protects your brand and your recipients. Here’s why it’s important:

Stops spoofing: Prevents hackers from sending fake emails using your domain.
Improves deliverability: Servers are more likely to accept emails from verified sources.
Reduces spam risk: Fewer legitimate emails end up in junk folders.
Builds sender reputation: Keeps your domain trustworthy and compliant with industry standards.

Creating an SPF Record

Identify your authorised servers.
List all IP addresses or hostnames of the servers (including any third-party providers) that are allowed to send emails on your behalf.
Define your SPF policy.
Specify which servers are allowed and decide what to do with unauthorised senders (e.g. reject, soft fail, etc.).
Publish it in DNS.
Add your SPF record as a TXT record in your DNS management system. Example: v=spf1 ip4:192.168.0.0/16 -all The v=spf1 identifies the version, and -all means emails from any non-listed servers should be rejected.

Checking Your SPF Record

Once added, DNS changes can take a while to propagate. Use an SPF checking tool to confirm your record is valid and properly formatted. If your setup involves multiple providers or complex routing, involve your IT team — it’ll save you hours of troubleshooting.

SPF for Third-Party Vendors

If you use external services (like marketing platforms or CRM tools) to send emails, you’ll need to include them in your SPF record.

Example:
If your provider is SuperEmails.net and their SPF domain is spf.superemails.net, your SPF record should look like this:

v=spf1 include:spf.superemails.net -all

⚠️ Important: Never publish more than one SPF record per domain. Use the include: mechanism to combine multiple authorised sources.

SPF Limitations

While SPF is essential, it’s not perfect:

Forwarding can break it. When an email is forwarded, the new sender’s server may not appear in your SPF record.
Complexity grows with scale. Managing SPF records becomes trickier as you add more sending sources.
No encryption or content verification. SPF checks only who sent the message, not what’s inside it.

This is why pairing SPF with DKIM and DMARC is vital. It closes the gaps SPF alone can’t cover.

Make SPF Even Better with Powermail

SPF does a great job verifying sending servers, but cybercriminals are creative. That’s why combining SPF with DMARC, powered by Quinset’s Powermail, gives your domain an extra layer of defence. All this he[s your emails reach inboxes safely and keeping fraudsters firmly out.