SPF Record Guide: What It Is, How It Works, and How to Configure It

Email attacks have increased over the years, and many fake emails look real enough to trick both users and email systems. Criminals often send emails from addresses that appear to belong to known companies, banks, or trusted websites. When a domain gets used for fake emails, inbox providers lose trust in it. One of the most important tools is the Sender Policy Framework (SPF). SPF checks whether the server sending an email is allowed by the domain owner. When SPF is set correctly, inbox providers can identify real messages more accurately and filter out fake ones. This guide explains what an SPF record is, how it works, and how you can set it up for safer and more reliable email delivery.

SPF records play an important role in maintaining email safety. Notify the receiving server which mail server is allowed to send mail to the domain and contribute to the prevention of spam, phishing and mail delivery problems.

What Is an SPF Record?

An SPF record is a type of DNS TXT record created to enumerate all servers and services allowed to send mail to a domain. Upon receiving an email from a domain, the incoming mail server checks the SPF record and verifies that the sending server is included in the approval list.

Records always start with version tags:

v=spf1

This tag tells the mail server that the record complies with the SPF standard. After this tag, list the rules that define which IP addresses, outgoing services, and domain mailing permits.

In simple words:

SPF tells the world which mail servers are allowed to send emails from your domain.

SPF contributes to domain protection and improved email performance. The main advantages are:

1. Protects Your Domain From Spoofing

SPF blocks fraudulent servers that send emails under the guise of your domain. If SPF is enabled, the receiving server can immediately detect that the fake mail has been sent from a server not listed on the SPF record. This prevents malicious messages from exploiting your name and protects your customers from fraud.

2. Improves Your Email Deliverability

Receiving providers such as Gmail, Outlook, and Yahoo trust domains with proper authentication. Emails from domains with valid SPF records are more likely to reach your inbox rather than your spam folder. Correct SPF settings are particularly important for companies that use multiple email tools such as marketing platforms, CRM systems, and transaction mail services.

3. Supports DMARC for Stronger Protection

SPF is one of the main components of DMARC, a stronger email authentication policy. To make DMARC work properly, you need to configure SPF or DKIM (or both) properly. By configuring the SPF, you can configure DMARC later to tell you exactly how the sending server should handle mail that failed authentication.

SPF works by checking if the mail sending server is included in the SPF record of the domain. The process is completed in the following simple steps of how SPF works:

• Mail arrives at the receiving server.
• The server checks the SPF record of the source domain.
• Compare the IP address of the outgoing server with the permission server list.
• Returns SPF = Pass, SPF = Fail, SPF = SoftFail, SPF = Neutral, etc.
• The email provider combines this result with other checks to determine whether the email should be inbox, spam folder, or rejected.

The following is a detailed setup procedure.

Setting up SPF records may seem technical, but it's easy to follow clear steps. In this guide, we will identify the mail source, create the correct SPF syntax, publish it to DNS, and explain the verification to ensure reliable mail delivery in order.

Step 1: Identify All Authorized Sending Sources

Create a list of all servers and services that send emails to your domain. Many domains use multiple services unnoticed, and any leakage can cause SPF errors. You must include:

• Web hosting server
• Business email services (Google Workspace, Microsoft 365, etc)
• Marketing platforms (Mailchimp, Brevo, ConvertKit, etc)
• Transaction mail service (SendGrid, Amazon SES, Mailgun, etc)
• CRM Tools to Send Automatic Emails
• Support ticket system
• Custom applications to send emails from your domain

It is essential to grasp all sources before creating SPF records. If you overlook the service, the email from the service may fail to authenticate.

Step 2: Construct the SPF Record Syntax

All SPF records start with version tags:

v=spf1

After that, add mechanisms and rules that define the target to allow mail transmission.

Common SPF Mechanisms

1. ip4:Used to allow specific IPv4 addresses or ranges.

Example:ip4:192.168.1.1

2. ip6:Used to allow IPv6 addresses.

Example:ip6:2001:db8::1

3. include:Allow by including SPF records for third-party services.

Example:include:sendgrid.net

4. a: Allow mail transmission from domain A record IP.

5. mx:Allow mailing from servers listed on the domain's MX records.

Choosing the Final Qualifier

At the end of the SPF record, add a modifier that tells you how the incoming mail server treats unauthorized senders.

SoftFail (~all):

Pass the email, but mark it as suspicious.

Used for testing and setting SPF for the first time.

HardFail (-all):

Reject all emails not listed on SPF records.

Use only after full testing.

Example SPF Syntax

Basic Example:

v=spf1 ip4:192.168.1.10 include:sendgrid.net include:_spf.google.com ~all

Step 3: Publish the SPF Record in Your DNS

To publish an SPF record:

• Log in to your domain registrar or hosting provider.
• Go to DNS management screen.
• Create a new TXT record.
• Enter @ (root domain) in the "Name" field.
• Paste the complete SPF record into the Value field.
• Save the record.

DNS updates may take minutes to hours depending on the provider.

Step 4: Validate the SPF Record

After the record release:

• Check the operation with the online SPF checker.
• Send a test email to your Gmail, Outlook, Yahoo inbox and check the header.

Check the results below:

spf=pass

If you see fail, neutral, or softfail, please review the following:

• IP Address
• include: mechanism
• DNS lookup count (must be less than 10 times)

Step 5: Maintain and Update the Record

SPF is not a record you can leave when you set it. Be sure to update the following:

• Add new email marketing tools
• Change your hosting provider
• Add CRMs and billing systems with email sending capabilities
• Stop using the transmit service
• Change your IP address

Also, be aware of DNS lookup restrictions. SPF allows up to 10 DNS lookups. Exceeding this limit will disable the entire record.

Slight errors in SPF settings can cause email delivery problems and put domains at risk of spoofing. Understand the most common errors to avoid problems and ensure that emails are delivered to the recipient.

1. Using +all Qualifier

+all modifiers allow virtually any server to send emails under the guise of your domain. This disables SPF objectives and makes domains vulnerable to spoofing and phishing attacks. Always avoid +all and use ~ all or -all instead for proper protection.

2. Creating Multiple SPF Records

Only one SPF record can exist in the domain. When multiple records are added, the SPF check fails completely. To avoid this, integrate all authorized outgoing servers and services into one SPF record. With proper integration, emails from all legitimate sources pass authentication.

3. Exceeding DNS Lookup Limit

Up to 10 DNS lookups for SPF records. include: Overuse of commands and mechanisms exceeds this limit and fails SPF validation. If you need a large number of services, consider flattening the SPF record or reviewing unnecessary entries to fit them within the limits.

4. Forgetting to Update When Services Change

When adding, deleting, or replacing an email service, be sure to update the SPF record. If you fail to update, a legitimate email may fail to check SPF and be marked as spam. Check SPF records regularly to match your current email settings.

5. Missing IP Addresses for Custom Servers

If you are running your own mail server or sending emails in a custom application, you must include those IP addresses in your SPF record. If these addresses are not listed, email authentication fails, the delivery rate decreases, and the risk of the message being flagged as suspicious increases.

SPF is one of the simplest and most effective ways to protect your domain from fake emails. Validate the entity that can send the domain on your behalf and support secure and reliable email delivery.

However, SPF alone cannot solve all email security issues. For complete protection, DKIM and DMARC should also be configured to build a strong authentication system. If you are managing your website, online store or business email, take a few minutes to check your SPF records. Make sure that all services are included and that you do not exceed the DNS lookup limit.

The correct SPF settings help your messages reach your inbox, protect against domain exploits, and build trust with your customers.