An email is an essential tool for businesses, and most of us rely on it daily for communication. However, as the number of email users has grown, so has the problem of spam, email spoofing, phishing, and email fraud. These types of attacks can cause significant harm, including loss of reputation, financial loss, and data breaches. To prevent such attacks, businesses must take proactive steps to secure their email systems. One of the ways to do that is by configuring an SPF setup.

Major email providers like Yahoo Mail and Google Workspace recommend email authentication protocols like Sender Policy Framework (SPF), DomainKeys Identified Mail (DKIM), and Domain-based Message Authentication, Reporting, and Conformance (DMARC) to protect email recipients from potential fraud.

Key Takeaways

Email authentication protocols like SPF are essential tools for preventing email spoofing and fraud.
Setting up a valid SPF record involves specifying authorized email servers through DNS configuration.
Regularly updating your SPF records is crucial to ensure new sending sources are recognized and unauthorized users are blocked.
Testing your SPF record helps verify that it is configured correctly and functioning as intended.
SPF works best in conjunction with DMARC to provide a stronger defense against email fraud and impersonation attacks.

SPF in Email Security – Explained

What is SPF? SPF stands for Sender Policy Framework. An email authentication protocol allows you to specify which servers are authorized to send emails to your domain. SPF works by adding a DNS record to your domain’s DNS configuration, which lists the IP addresses of your email servers. This record tells other email servers that any emails sent from your domain that do not come from authorized IP addresses should be rejected.

Setting up a valid SPF record is essential to prevent unauthorized users from sending emails using your domain name. For example, spammers or attackers may use your domain name to send spam or phishing emails, which can cause harm to your reputation, lead to blocking, and compromise the security of your customers and employees.

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SPF Components

The main components of an SPF record in DNS are as follows:

Version (v=spf1):
Specifies the SPF version, always starting with v=spf1.
IP4 and IP6 (ip4: / ip6:):
Lists authorized IPv4 and IPv6 addresses allowed to send emails for the domain.
A and MX Mechanisms (a: / mx:):
- a: allows emails from servers whose IPs match the A record of the domain.
- mx: allows emails from servers listed in the domain’s MX (Mail Exchange) records.
Include Mechanism (include:):
Permits other domains’ SPF records to authorize senders, useful when third-party services send emails on behalf of your domain.
All Mechanism (all):
Sets a default rule at the end of the SPF record. The options are:
- -all: Hard fail (reject non-authorized IPs).
- ~all: Soft fail (mark non-authorized IPs as suspicious).
- ?all: Neutral (no action taken on non-authorized IPs).
- +all: Pass (allows all IPs, rarely recommended).
Redirect (redirect=):
Points to another domain’s SPF record if you want to use it instead of creating your own.
Modifiers:
Optional rules for fine-tuning, though less common.

SPF Example

v=spf1 ip4:192.168.1.1 include:_spf.thirdparty.com -all

This example allows emails from 192.168.1.1 and includes a third-party SPF record, rejecting emails from other IPs with -all.

Mastering SPF Settings

An SPF setup refers to the SPF email authentication protocol configuration in the DNS of a domain owner. An SPF setup allows you to authorize your legitimate sending sources, making sure receiving servers can easily demarcate between a genuine email sender and one who is merely impersonating a legitimate domain name. It’s a necessary step in email validation, to aid in protection against email-based cyberattacks.

How to Setup and Add SPF Records

An SPF setup is not only essential for your active sources but also for your non-sending domains to guarantee they are safe against malicious usage. Setting up an SPF record is a straightforward process, and it involves the following steps:

Step 1: Determine Your Email Servers

The first step is to determine which servers are authorized to send emails for your domain. These servers can include your mail server, any third-party email service provider you use, or any other server that sends emails using your domain name.

Step 2: Create an SPF Record

Once you have identified your authorized email servers, you can create an SPF record using an SPF record generator tool. An SPF record is a TXT (text) record in your domain’s DNS configuration, which is essential for your SPF setup. You can use a simple syntax to create your SPF record, such as:

v=spf1 ip4:<IP address> -all

In this example, the “v=spf1” indicates that this is an SPF record, and “ip4:<IP address>” indicates the IP address of the authorized email server. The “-all” at the end indicates that any emails that do not come from authorized IP addresses should be rejected.

Step 3: Publish Your SPF Record

After creating your SPF record, you need to publish it in your domain’s DNS. Domain administrators and make the required DNS updates to activate the protocol easily. You can do this by logging in to your DNS provider’s website and adding a new TXT record with your SPF record. Alternatively, you can ask your IT team or hosting provider to do this for you.

Step 4: Test Your SPF Record

Once you have published your SPF record, it is essential to test it to make sure that it is working correctly. You can use online SPF record checkers, such as the one provided by MXToolbox, to test your SPF record. These tools will tell you whether your SPF record is valid and whether it is configured correctly.

5 Misconceptions About SPF Records

There are certain SPF record myths doing rounds on the internet that may lead to people making incorrect decisions. Let’s bust them one by one:

1. SPF Alone Can Prevent Spoofing

This is untrue. Setting up SPF alone cannot prevent cyber attacks like spoofing or impersonation. In order to prevent them, SPF needs to be combined with DMARC (Domain-based Message Authentication, Reporting, and Conformance) which allows domain owners to reject fraudulent emails sent from their own domain.

2. You Can Use +all in Your SPF Record

Using +all allows any server to send emails on behalf of your domain. This negates the purpose served by the SPF protocol. Instead, ~all or -all are recommended to use in order to deploy SPF effectively for your domain.

3. SPF Works for Forwarded Emails

We all wish that was true. Unfortunately, in mail forwarding scenarios SPF breaks, due to changes in header information made by intermediary servers. In such cases, protocols like DKIM or preferably ARC can come in handy for effective email authentication.

4. SPF Records Have Unlimited DNS Lookups

RFC specifies a maximum of 10 DNS lookups for SPF records, exceeding which leads to an SPF permerror result. It is essential to use SPF optimization methods like flattening, or preferably SPF Macros, to make sure you are always staying within the SPF limits.

5. With SPF You Can “Setup and Forget!”

Don’t make this SPF mistake! You need to update your SPF records from time to time so that your updated sender list gets to send emails on behalf of your domain! This is an important step to ensure legitimate emails dont get blocked by your receiver’s server.

How Does SPF Record Work?

The domain owner creates an SPF record manually or using an online tool that specifies sending sources that are permitted to send emails on behalf of the domain.
When an email is sent, the receiver’s server performs a DNS query on the sender’s DNS to look up the SPF record and check for authorized sources.
If there is a match the email lands safely in the inbox, else the email may be flagged as suspicious. This depends on the action qualifier (~all, -all, ?all) defined by the domain owner in the SPF record.

Tips for an Accurate SPF Setup

Here are some tips for creating a strong SPF record setup:

Include all authorized email servers: Make sure to include all authorized email servers to send emails for your domain in your SPF setup. This can include your mail server, third-party email service providers, or any other server that sends emails using your domain name.
Use the “-all” mechanism: The “-all” mechanism at the end of your SPF record tells other email servers to reject any emails that do not come from authorized IP addresses. This is a critical step to prevent unauthorized users from sending emails using your domain name.
Use the “include” mechanism: The “include” mechanism allows you to include SPF records from other domains. This can be useful if you use a third-party email service provider to send emails for your domain. You can include their SPF record in your SPF setup to make sure that emails sent from their servers are also authenticated.
Use the “~all” mechanism for testing: The “~all” mechanism tells other email servers to mark any emails that do not come from the authorized IP addresses as “soft failures.” This means that these emails will still be delivered, but they will be marked as suspicious. You can use this mechanism during testing to make sure that your SPF record is working correctly without immediately rejecting emails.
Keep your SPF record up to date: As your email infrastructure changes, make sure to update your SPF record to reflect these changes. This can include adding new email servers or removing old ones.

Benefits of Optimizing Your SPF Settings with PowerDMARC

The DNS lookup limit is a restriction imposed by email servers. It limits the number of DNS lookups that can be performed when verifying an email’s SPF record. This limit is typically set at 10 DNS lookups, and if the email server exceeds this limit, SPF may break and cause email deliverability issues.

SPF flattening is a technique used to reduce the number of DNS lookups required to verify an email’s SPF record. It works by combining multiple SPF records into a single record, which can reduce the number of DNS lookups required to authenticate an email.

Here’s an example of how SPF flattening can help:

Let’s say your company uses several third-party services to send emails. This may include marketing automation software, a helpdesk system, and a CRM tool for small businesses. Each of these services will be added to the IP address list in your DNS SPF record or individual SPF records for each of these services, and if you were to include all of them in your domain’s SPF record, it would exceed the 10 DNS lookup limit.

By using SPF flattening, you can combine all of these redundant IPs into a single include. This means that when an email server performs a DNS lookup to verify your SPF record, it only needs to perform a single lookup or a few lookups, rather than multiple lookups for each of the individual SPF records and IP addresses.

To Sum It Up

An SPF setup is a crucial step in securing your email system and preventing email fraud. By creating an SPF record and publishing it in your domain’s DNS configuration, you can make sure that emails sent from your domain are authenticated and prevent unauthorized users from sending emails using your domain name. Following the tips outlined above, you can create a strong SPF record and secure your email system.

FAQs on Setting Up an SPF Record

Can I Split a Large SPF?

Splitting up a large SPF record into smaller ones is not recommended due to SPF character limits and the added restrictions against publishing more than one SPF record for the same domain. Instead, try these tactics:

Make your SPF record simple and concise
Use fewer includes and combine IP ranges
Use SPF management solutions and third-party services

Why Is SPF Record Used?

An SPF record is used to ensure that only authorized sources are allowed to send emails on your domain’s behalf, limiting external exposure and impersonation attempts.

When Do You Need SPF?

As an email authentication protocol, SPF is needed to ensure email communications can be verified for authenticity and comply with the latest industry mandates. Learn more about the importance of SPF configuration.

How to Optimize SPF Record?

You can optimize your SPF record manually by accessing your DNS and making the required changes. However, a more hassle-free and easier option is to deploy third-party SPF optimization services that offer flattening or Macros optimization for SPF record management.

How Do I Know My SPF Record is Set?

You can check your SPF record using an online SPF record lookup tool in order to confirm whether your SPF record is set correctly.

About
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Ahona Rudra

Domain & Email Security Expert at PowerDMARC

Ahona is the Marketing Manager at PowerDMARC, with 5+ years of experience in writing about cybersecurity topics, specializing in domain and email security. Ahona holds a post-graduation degree in Journalism and Communications, solidifying her career in the security sector since 2019.

How to Set Up SPF Record? – SPF Setup Guide