What is SPF For Email?

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SPF (Sender Policy Framework) is an email authentication protocol that helps senders verify the source of emails sent from their domain name.

by Maitham Al Lawati

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What is SPF For Email?
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SPF stands for Sender Policy Framework. It is an email authentication protocol designed to detect email spoofing and prevent unauthorized senders from sending messages on behalf of a particular domain. 

SPF email records help maintain a list of verified senders for your domain that can be publicly looked up and retrieved by receiving servers to authenticate emails and are mentioned under RFC 7208.

Key Takeaways

  1. SPF is an essential email authentication protocol that helps prevent email spoofing by verifying sending servers.
  2. Implementing SPF can significantly improve your email deliverability rates and reduce the chances of legitimate emails being marked as spam.
  3. Managing SPF records can become complex as the number of authorized servers and third-party services increases.
  4. SPF alone does not provide encryption or content verification, making it important to pair it with DKIM and DMARC for enhanced security.
  5. Regularly reviewing and updating your SPF records is crucial to maintaining email security and compliance with best practices.

 

How does SPF work?

How does SPF work

SPF works by allowing domain owners to publish a list of authorized email servers (IP addresses or hostnames) that are allowed to send emails on their behalf. Here is how SPF works step-by-step: 

1. Publishing your record for SPF

The domain owner publishes an SPF record in the DNS of their domain. This record specifies which email servers are authorized to send emails to that domain.

2. Your email is received

When an email is sent, it contains information about the sender’s domain.

3. Extracting the Sender’s Domain

The recipient’s email server extracts the domain from the sender’s email address.

4. DNS lookup is performed

The recipient’s email server performs a DNS lookup to retrieve the SPF record of the sender’s domain.

5. SPF authentication is performed

The SPF record contains a policy that defines which servers are allowed to send emails for the domain. The recipient’s email server compares the IP address or hostname of the server that sent the email against the list of authorized servers specified in the SPF record.

6. Final authentication result is determined

Based on the SPF check, the recipient’s email server determines whether the email came from an authorized server or not.

7. Action is taken based on the results

The recipient’s email server takes action based on the SPF check result. It could accept the email, or even mark it as spam.

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How to use SPF With Your Email

To use the SPF email standard, you must make sure you have a proper understanding of how it works, and check your domain’s and email service provider’s SPF support. Following this, you can create a record for SPF, publish the record on your DNS, and ideally combine your SPF DNS implementation with DKIM and DMARC to prevent spoofing. 

How to Enable SPF For Your Email

To create an SPF record, you need to follow these general steps:

Determine the authorized email servers

Identify the IP addresses or hostnames of the email servers that are authorized to send emails on behalf of your domain. This may include your own organization’s email servers or third-party email service providers.

Define your SPF policy

Determine the policy for SPF. This involves specifying which servers are allowed to send emails for your domain. You can choose to either allow only specific servers or include a range of servers based on IP addresses or hostnames.

Determine SPF Format

SPF records are published as a TXT record in your domain’s DNS. The record should be in a specific format and contain the necessary information.

Publish the SPF record

First, generate your SPF record with our free SPF generator tool. Then, access your domain’s DNS management system, which is typically provided by your domain registrar or hosting provider. Locate the DNS settings for your domain and add a new TXT record containing your SPF record. Specify the hostname (usually “@” for the domain itself) and paste the SPF record in the value field.

SPF Record Example

SPF record TXT in your DNS will look like this:

SPF Record example

This record defines a set of hosts as valid senders for all messages sent through the server at 192.168.0.0/16, but it does not specify where those messages will be delivered—they could be delivered locally or they could be delivered by another server on the Internet, depending on how the other servers are configured in the email infrastructure (which we’ll get into later).

How to Check & Verify SPF?

Once you’ve set up your SPF record, it may take some time for the changes to propagate across the DNS system. Use our SPF record check tool to verify the correctness of your record and ensure it is being recognized by the DNS.

It’s important to note that SPF records can be complex, depending on the specific requirements of your email infrastructure. If you’re unsure about the syntax or need more advanced configurations, it’s recommended to consult your system administrator or IT support for assistance in creating the SPF record correctly.

SPF for Third-Party Vendors

What is SPF for your third-party vendors? To align your third parties for SPF, you need to include IP addresses or SPF-handling domains unique to them in your domain’s record. But beware, do not include multiple SPF records for the same domain! 

For example, if you are using SuperEmails.net as your email sender, and their SPF-handling domain is spf.superemails.net, your SPF record might be:

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

Why is Sender Policy Framework Important for Email?

SPF is important to ensure emails sent from your domain are genuine, and not fake lures created by cyberattackers to trick your customers. Here are some key benefits of SPF: 

Reduced Email Spoofing

SPF helps combat email spoofing by verifying the authenticity of the sending server. 

Improved Email Deliverability

Implementing SPF can enhance email deliverability rates. When recipient servers perform an SPF check and find that the sending server is authorized, they are more likely to accept the email rather than mark it as spam or reject it. 

Reduced False Positives

By accurately identifying authorized email servers, SPF reduces the likelihood of legitimate emails being marked as spam. This helps prevent false positives and ensures that important emails reach the intended recipients’ inboxes.

Enhanced Sender Reputation

SPF plays a role in building and maintaining a positive sender reputation. By implementing SPF, domain owners demonstrate their commitment to email security and authentication. 

Phishing and Spam Mitigation

SPF helps in reducing the effectiveness of phishing attempts and spam campaigns. SPF makes it more challenging for malicious actors to send fraudulent emails claiming to be from reputable domains. 

Compliance with Email Standards

Many email service providers and organizations encourage or require the use of SPF as part of their email policies. 

What are the Limitations of SPF?

While SPF does protect your domain against spam and forged sender addresses, it is not all perfect! Here’s why: 

  • SPF can encounter challenges with email forwarding. When an email is forwarded from one server to another, the original SPF authentication may fail because the forwarding server is not listed in the SPF record of the sender’s domain. 
  • As the number of authorized email servers and third-party services increases, the complexity of managing and maintaining SPF records grows. 
  • SPF focuses solely on verifying the authenticity of the sending server and does not provide encryption or content verification as DKIM does. 
  • SPF does not provide visibility into the specific sender of an email. It only validates the authenticity of the sending server. Therefore it becomes crucial to pair SPF with DMARC.

Make SPF Even Better With PowerDMARC

SPF by itself is still effective, but cybercriminals have come up with ways to bypass the IP address verification phase. But SPF technology is made relevant again by incorporating it into DMARC. 

We pair SPF with DKIM and DMARC

dmarc dkim spf report

Along with aligning DMARC against both SPF and DKIM, PowerDMARC takes this one step further with AI-based real-time threat modeling that uncovers spoofing attacks around the globe.

Reporting and Feedback

Neither SPF nor DKIM gives the domain owner feedback about emails that fail authentication. DMARC sends detailed DMARC reports directly to you, which the PowerDMARC app converts into easy-to-read charts and tables. Using the analytics data, you can change your email marketing strategy on the fly.

Control What Happens to Unauthenticated Email

DMARC lets you decide whether an email that fails validation goes to inbox, spam, or gets rejected. With PowerDMARC, all you have to do is click one button to set your DMARC policy. It’s that easy.

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