How Does SPF Work? Email Authentication Method Explained

SPF, when configured correctly, can help you land in the inbox.

It was developed to prevent spam and fraudulent emails.

If you implement it, internet service providers will reward you with better deliverability.

SPF is essential for effective email outreach, but how exactly does it work?

We’ll explain all that below. ⬇️

SPF vs Cybercrime

Email spoofing is pretending to be sending from a domain when it’s really coming from somewhere else.

Through email spoofing, criminals can commit cyber crimes like phishing attacks and spread malware.

Email authentication methods, like SPF, aim to prevent this.

Setting up SPF is a good step toward effectively combating email cybercrime.

When ISPs notice you send authenticated emails, you have a better chance of avoiding the spam folder.

How Does SPF Work? 👷

Upon receiving an email, the receiving server checks if the sending server is authorized to send email from that domain.

If the sending server is indeed authorized, the email gets delivered normally.

But if it’s not, the authentication fails, and the email may get rejected.

💡A sending server is usually the tool you use to send emails. In other words, your email service provider. This could be Google, Office 365, or MailChimp.

So, how do email servers get authorization to send from a domain?

Simple. The servers that are allowed to send from a domain are added to the SPF record associated with that domain.

In other words, you decide which servers can send from your domain.

SPF Record 📝

An SPF record is a DNS record that needs to be added to a domain’s DNS settings. It’s basically a line of text that looks like code.

v=spf1 include:somesendingservice.com -all

The include tag holds the email server that’s allowed to send from the domain.

You can add more servers by adding multiple include tags or by adding IP addresses to the record:

v=spf1 ip4:192.168.0.1 ip4:203.0.113.10/24 include:spf.example.com -all

Here’s what the rest of the record means:

V stands for version. There are two versions of SPF, but only the first one is widely adopted. So, spf1 starts the majority of SPF records.

Apart from the includes and IP addresses, which hold authorized server information, there’s only one component left to explain: the -all tag.

It instructs the receiving server to reject emails that fail authentication.

If this tag is set to ~all, then the receiving server will be more lenient with emails that fail authentication.

It may mark the emails as spam but will still deliver them.

SPF and Your Technical Setup 🧑‍💻

Before starting email outreach, having your technical setup in order is essential.

Your technical setup consists of the necessary DNS records and your custom tracking domain.

SPF is a vital component of your technical setup. It works in tandem with DMARC and DKIM to protect against spoofing and prevent cyber crimes.

With your technical setup on-point, internet service providers trust your emails more.

This increased trust leads to better open rates for your email outreach.

Another way to boost your open rates is through an email warm-up service like lemwarm.

lemwarm was developed to help keep your emails out of the spam folder.

It takes a few minutes to set up, but then it works diligently behind the scenes to boost your email deliverability.