What’s the Difference Between SPF DKIM and DMARC?

November 23, 2022

10 Min Read

SPF, DKIM, and DMARC are the three most important email authentication protocols to prove to mail servers and ESPs that senders are authorized to send emails on behalf of a specific domain. Implementing these protocols is vital to:

Prevent hackers from spoofing and sending fraudulent emails using your domain name.
Protect your clients, business partners, and organization from cybercriminals. Attempting to exploit your domain or domain name.
Garner trust among ESPs as a verified sender.
Prove to customers, government authorities, and other third parties that your organization takes email security seriously.
Enhance your email deliverability rates and avoid your messages landing in the spam or junk folders.

While all three standards are used for email authentication, they differ. Understanding SPF, DKIM, and DMARC protocols are vital to ensure that your emails are properly authenticated.

This article will discuss what SPF, DKIM, and DMARC stand for and how they’re used in email authentication. But before we discuss this, let’s explore how email works.

How Does Email Work?

The way email works is pretty straightforward. Before you can send or read emails from your device, you need a Mail User Agent or MUA, such as Gmail. The MUA interacts with the Mail Transfer Agent or MTA, also known as a mail server. The MTA helps to receive and store your emails remotely. You’ll only receive the mail on your device through the Mail Delivery Agent, or MDA, when you open your MUA.

The Simple Mail Transfer Protocol (SMTP) is a communication protocol responsible for sending emails to a mail server. Even though email providers like Gmail have internal protocols, they still use SMTP to send emails outside their systems. For instance, when a Gmail user wants to send a mail to a Yahoo! mail user.

Several protocols, such as POP3 and IMAP 4, have been designed to help you download emails from the server. Today, both protocols have been replaced by webmail, which allows you to login in and receive mail on any device worldwide. However, you need to be connected to the internet to use it.

Email protocols weren’t built with security in mind. Mail servers are only tasked with taking messages from the sender and delivering them to the recipient. But this has become an issue as the internet continues to expand, with spamming and phishing growing into prevalent problems for all email users.

At first, email users implemented the TLS (Transport Layer Security) encryption protocol to encode messages in transit. One of the loopholes in TLS is that it doesn’t offer protection for data at rest.

TLS protects data traveling from one MTA to another MTA, but each MTA can modify the message. SPF, DKIM, and DMARC were created to address this issue and provide a way for mail servers to validate the source of a message.

What is SPF?

The Sender Policy Framework, or SPF, is an email authentication protocol designed to help detect and prevent email spoofing. The authentication protocol allows you to create a DNS TXT record that lists the sender addresses you’ve authorized to send messages on your domain’s behalf. With this protocol, ISPs or email servers can validate that messages from a particular domain are legitimate.

Your domain administrator can easily create an SPF record and publish it in the DNS record as a TXT entry. Here are some things to include:

The version of SPF you want to use.
The IP addresses allowed to send messages using the domain.
Any third-party domains authorized to send emails on the domain’s behalf.
An ending “all” tag indicates the policy that applies when a mail server discovers an unauthorized IP.

When an email is sent to a recipient alleging to come from your domain or on your domain’s behalf, the receiving mail server will check for an SPF record. If it detects one, it retrieves the list of authorized IPs for the domain. If the sender’s IP matches one from the SPF record, the authentication check is marked as a “PASS,” and the recipient receives the message. Otherwise, the message is rejected or transferred to the spam folder.

What is DKIM?

DKIM stands for DomainKeys Identified Mail and is an email authentication protocol that allows you to sign your email digitally. It provides email security with a unique identifier using public key cryptography instead of an IP address.

Like SPF, DKIM requires a TXT record added to your DNS. DKIM uses encryption to create public and private cryptographic keys. The private key remains on your server and is used to digitally sign every email, while the public key is placed in the DKIM record.

When you send an email to a receiver, the recipient server retrieves the DKIM record and uses the public key to decode the DKIM signature and hash it. Then, the receiving server compares the private and public hashes to see if they match. If they do, the message is authentic and unaltered and won’t be considered spam. Otherwise, the message is not from a legitimate sender, or it has been modified in transit so it fails DKIM authentication and won’t be delivered to the recipient’s inbox.

DKIM helps to validate three things:

The content of the mail hasn’t been modified or tampered with.
The email headers didn’t change since the sender sent the message.
The domain owner authorizes the email sender.

Creating your DKIM record is easy, as most email servers have native DKIM functionality. Regardless of the provider you use, the following information should be included:

S – This is the selector that represents the record name used with the domain to find the public keys in the DNS record.

D–This is the sender’s domain, and it’s used alongside the selector record to locate the public key.

P– This public key that’s included in the DNS record.

While other tags are available, the three vital elements of generating a DKIM record are the above.

What is DMARC?

DMARC stands for Domain-based Message Authentication, Reporting, and Conformance. This email authentication, policy, and reporting protocol leverages and enhances DKIM and SPF to validate the authenticity of a message using the “from” address. This helps to prevent email spoofing and phishing attacks. This authentication protocol has three primary purposes:

It validates whether both DKIM and SPF protect an email. It verifies that the visible “from” address matches the domain in the return-path address (for SPF) and the DKIM header (for DKIM).
It specifies how email receivers should handle messages that fail the authentication checks.
It allows the receiving server to send a report to the sender regarding messages that pass or fail the DMARC authentication checks.

For an email to pass DMARC authentication, it must pass DKIM and/or SPF. So if DKIM fails and SPF passes, the message will still be delivered. To implement DMARC, you must create a DMARC record and define the policy you want based on your needs. The available policies you can deploy include the following:

Policy = (P=none) – Also called the monitoring policy. Here, no action is taken, and the message is delivered to the recipient regardless of whether it passes or fails DMARC authentication.

Policy = (P=quarantine) – This policy sends messages failing DMARC authentication to the spam or quarantine folder.
Policy = (P=reject) – The reject policy blocks emails failing DMARC authentication and sends them back. It’s the ultimate policy to strive towards.

Are All Three Measures Required?

Deciding which email authentication protocol to implement can be confusing. Though all three measures are authentication protocols that strengthen your email security, none can stand alone. DMARC, SPF, and DKIM all play a vital role in ensuring your email is protected and delivered as intended. You must implement all three protocols to have complete security.

While SPF can prevent domain spoofing on its own, implementing SPF alone doesn’t provide any protection against email fraud. DKIM can verify the legitimacy of a sender, but hackers can still modify the visible “from” address.

For well-rounded and robust email security protection, we recommend you implement DKIM, SPF, and DMARC protocols.

Why You Need DMARC, SPF, and DKIM

Implementing these three vital authentication protocols enhances your email security significantly and:

Signals to the world that your organization is legitimate and takes email security seriously.
Improves email deliverability rates and nurtures brand trust since hackers will find it difficult to spoof your domain for fraudulent activities.
Protects your customers, partners, and other third parties from fraudulent exploits in your domain name.

By verifying the legitimacy of a sender, SPF, DKIM, and DMARC combine forces to prevent email spoofing and phishing attacks.

How to Get Started with SPF, DKIM, and DMARC

When setting up your SPF, DKIM, and DMARC policy, it’s essential you do it in the correct order. Remember that implementation is a multi-stage process that takes time to reach ultimate DMARC compliance with SPF and DKIM. Fortunately, we have an extensive range of free tools and managed solutions to help you achieve that.

DMARC compliance starts with SPF. Implement this protocol first by creating your SPF record. With EasyDMARC, you can easily:

Check your SPF records to see whether an SPF record is published for your domain and if it’s deployed correctly.
Generate your SPF record instantly without worrying about syntax typos and errors.
Validate your SPF record before publishing it to your DNS to ensure the correct configuration.
Use our EasySPF tools to solve any other configuration issues like the common “too many DNS lookups” error.

DKIM is the next step to DMARC compliance. Once SPF is up and running smoothly, it’s time to implement DKIM. With EasyDMARC you can:

Check your DKIM records to see if any exist on your domain and whether they’re valid.
Generate your DKIM record within seconds for your dedicated mail servers.

Once you’ve confirmed that DKIM is up and running correctly, you can focus on DMARC deployment. With EasyDMARC you can easily:

Check your domain’s DMARC status with ours. DMARC record checker.
Generate your DMARC record swiftly and correctly before publishing it in your DNS.
Set up and analyze your DMARC failure reports in an easy-to-understand format.
Use our XML aggregate reports analyzer for instant insights into your email infrastructure.
Use our managed DMARC solution for one-click DMARC enforcement and management across all of your domains.

If you need help at any stage of your SPF, DKIM, and DMARC journey, feel free to contact us. Our expert team can guide you through the various processes and stages.

Conclusion

We’ve discussed SPF, DKIM, and DMARC and how they work. These authentication protocols are vital for every organization looking for robust email protection. While DMARC deployment requires technical expertise, EasyDMARC has designed various tools to make your DMARC journey seamless. With our managed solution, DMARC deployment has never been easier. Sign up today!