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SPF (Sender Policy Framework) 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.
SPF stands for Sender Policy Framework and was first introduced in the early 2000s. While SPF was earlier an acronym for Sender Permitted From ( also called SMTP+SPF), in February of 2004, SPF came to be known by the popular acronym that we are familiar with today, which is: Sender Policy Framework.
SPF in email 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:
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.
When an email is sent, it contains information about the sender’s domain.
The recipient’s email server extracts the domain from the sender’s email address.
The recipient’s email server performs a DNS lookup to retrieve the SPF record of the sender’s domain.
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.
Based on the SPF check, the recipient’s email server determines whether the email came from an authorized server or not
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The recipient’s email server takes action based on the SPF check result. It could accept the email, or even mark it as spam.
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.
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:
SPF helps combat email spoofing by verifying the authenticity of the sending server.
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.
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.
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.
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.
Many email service providers and organizations encourage or require the use of SPF as part of their email policies.
To create an SPF record, you need to follow these general steps:
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.
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.
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. Here’s an example of an SPF record:
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 TXT in your DNS will look like this:
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).
Once you’ve added the 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.
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
We have got you covered. Our knowledge contains a list of famous third-party email vendors with specific instructions on how to configure the protocol for each of them.
While SPF does protect your domain against spam and forged sender addresses, it is not all perfect! Here’s why:
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.
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.
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.
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.
Maitham Al Lawati
Maitham is a tech entrepreneur, cybersecurity expert, CEO and Founder of PowerDMARC with 15+ years of industry experience. Maitham holds a Global MBA from the University of Manchester and various professional certifications including CISSP, CISM, CRISC, and ISC2 CCSP.
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