Sender Policy Framework (SPF) is a vital security technology that helps protect against online attacks and spam emails. 

Email spoofing, phishing attacks, and spam are widespread threats that can lead to data loss, financial damage, and harm to reputation. SPF helps combat these threats. You can enhance the security of your emails and ensure they reach your intended recipients without being flagged as spam.  

Let’s explore SPF records and their role in email security. 

What is SPF for email? 

Sender Policy Framework is an email authentication protocol that allows domain owners to specify which mail servers are authorized to send emails on behalf of their domain. When an email is sent, the receiving mail server can check the SPF record published in the domain’s DNS settings to verify if the sending mail server is allowed to send emails for that domain. 

What Is an SPF Record?  

It’s a special text file that you add to your website’s settings. This file lists all the email servers that are allowed to send emails using your domain name 

This helps prevent spammers from pretending to be you when they send emails, which protects your domain’s reputation and helps ensure that your emails reach your intended recipients safely. 

Example of an SPF Record  

Here’s an example of an SPF record for BigRock.in: 

v=spf1 include:_spf.bigrock.in ~all 

In this record, v=spf1 indicates that this is an SPF record. include:_spf.bigrock.in specifies that the SPF record for bigrock.in includes the SPF settings from the _spf.bigrock.in domain.  

The ~all at the end specifies the default policy, which is to soft fail (tilde) for all other servers not explicitly listed, meaning they are not strictly prohibited but are treated with caution. 

How Does an SPF Record Work? 

DNS (Domain Name System) record that helps prevent email spoofing and phishing attacks by specifying which mail servers are allowed to send emails on behalf of a specific domain. 

When an email is sent, the receiving mail server checks the SPF record of the sender’s domain. If the sending mail server’s IP address is listed in the SPF record as authorized, the email is considered legitimate. 

If the sending server is not listed in the SPF record, the receiving server may mark the email as spam or reject it altogether. 

For instance, BigRock uses email to communicate with customers. An SPF record is like a list you make defining the specific servers that can send emails for BigRock. When someone gets an email from @bigrock.in, the receiver’s email server checks this list. If the sending server is on the list, the email is okay. If not, it might be fake and could get blocked.  

SPF records are published in the DNS settings of a domain and typically look like a TXT record with specific syntax defining the allowed IP addresses or hostnames of authorized mail servers. 

What are the Components of an SPF Record? 

1. Version Number:  

The “v=spf1” at the beginning of an SPF record indicates that the record is using SPF version 1. This version number is essential for compatibility and helps email servers understand how to interpret the SPF record. It tells receiving servers that the SPF record follows the SPF version 1 specification, which includes the syntax and rules for defining which mail servers are authorized to send emails on behalf of the domain. 

If a different version number or an incorrect format is used, it could lead to SPF records being misinterpreted or ignored, potentially affecting the delivery and handling of emails sent from the domain. 

2. Mechanisms:  

Mechanisms in SPF records specify the criteria for allowing or rejecting emails sent from a domain. They determine which IP addresses or hostnames are authorized to send emails on behalf of the domain. Here are some common mechanisms: 

  • ip4: Specifies IPv4 addresses that are allowed to send emails. For example, “ip4:” allows the IPv4 address to send emails. 
  • ip6: Similar to ip4 but for IPv6 addresses. For example, “ip6:2001:db8::1” allows the IPv6 address 2001:db8::1 to send emails. 
  • a: Allows the domain’s A record to be used as an authorized sending host. For example, “a” allows the IP address of the domain to send emails. 
  • mx: Allows all hosts listed in the domain’s MX (Mail Exchange) records to send emails. This is useful when email is handled by a third-party mail server. 

READ: IPv4 vs IPv6 — Differences Between the Two Protocols 

3. Quantifiers: 

Quantifiers specify how the mechanism should be processed. Common quantifiers include “+” to pass, “-” to fail, and “~” to soft fail (mark as spam but not reject). 

Here’s more information on these quantifiers: 

  • + (Pass): If the sending server’s IP address matches the mechanism, the SPF check should pass, and the email should be accepted. 
  • (Fail): If the sending server’s IP address matches the mechanism, the SPF check should fail, and the email should be rejected. 
  • ~ (SoftFail): In case the sending server’s IP address matches the mechanism, the SPF check should result in a “soft” failure. The email is still accepted, but it may be marked as spam or treated with suspicion. 

4. Modifiers:  

Modifiers in SPF records provide additional instructions or features to enhance the SPF policy. They can be used to customize and enhance the behavior of SPF records, providing more flexibility in managing email authentication policies. 

Common modifiers include: 

  • redirect: Redirects SPF checks to another domain’s SPF record. This is useful for domains that want to delegate their SPF policy to another domain. For example, “redirect=example.com” directs the receiving server to check the SPF record for “example.com” instead 
  • exp: Provides an explanation for SPF policy failures. This modifier is used to create a human-readable explanation that can be included in the SPF failure message. For example, “exp=Explanation text” provides a custom explanation for why the SPF check failed. 

How To Create, Add, and Edit SPF Records  

To create, add, or edit SPF (Sender Policy Framework) records for your domain, follow these steps: 

Understand SPF Basics:  

Before creating or editing SPF records, understand how SPF works and the syntax of SPF records. 

Access Your Domain’s DNS Settings:  

Log in to your domain registrar or DNS hosting provider’s website to access your domain’s DNS settings. Look for options to manage DNS records or edit DNS settings. 

Create a New SPF Record:  

If you don’t have an SPF record yet, create a new one. Use the following format for a basic SPF record: 

v=spf1 include:_spf.example.com ~all 

Replace _spf.example.com with your domain or the domain you’re using for SPF records. You can also include specific IP addresses or mechanisms as needed. 

Add or Edit an Existing SPF Record:  

If you already have an SPF record and want to add or edit it, locate the existing SPF record in your DNS settings and make the necessary changes. 

Verify Your SPF Record:  

After creating or editing the SPF record, verify its correctness using SPF record checkers available online. Ensure that there are no syntax errors or misconfigurations. 

Publish the SPF Record:  

Save the changes in your DNS settings to publish the SPF record. It may take some time for the changes to propagate across DNS servers. 

Monitor and Maintain:  

By regularly performing SPF record checks, domain owners can ensure that their SPF records are correctly configured, which helps prevent email spoofing and improves email delivery. 

Choosing a reliable hosting provider is important for Sender Policy Framework because they offer domain owners tools and support to set up SPF records correctly. Reliable providers also help troubleshoot issues, ensuring your emails reach their destination safely. 


Web hosting specialist with a knack for creativity and a passion for baking, serving up tech solutions with a side of sweetness.