What is SPF?

SPF Explained

SPF (Sender Policy Framework) is an email authentication system that works by verifying the IP address of any message sent from a specific domain. SPF allows ISPs and email services to make sure that the messages they receive are actually coming from a legitimate source. SPF assists in preventing spoofing, which occurs when someone masquerades as another person or organization in order to send malicious emails. SPF provides basic protections against phishing threats when someone attempts to trick users into revealing sensitive information by sending fake messages that appear to be from a legitimate source. 

How does SPF work?

SPF works by comparing the IP address of the message with a list of approved IP addresses associated with the domain from which it was sent. If the message is coming from an IP address that is not on that list, SPF will reject it and mark it as spam or suspicious. SPF also helps to protect domains from being used to send malicious emails by stopping email spoofing. SPF uses a DNS record to authorize which IP addresses are allowed to send emails from that domain, making it harder for attackers to spoof the sender address.

The Challenges with SPF

Although SPF is effective at blocking malicious emails from reaching users, SPF does not provide 100% protection against all types of email attacks. SPF is limited by the fact that it only authorizes IP addresses and does not 'authenticate' that the message was sent from a legitimate source. SPF also has difficulty recognizing dynamic IP addresses, which can lead to SPF lookups failing and resulting in legitimate emails being blocked. SPF is also not able to detect forged headers, which are used by attackers to disguise the true source of malicious emails.

For these reasons, SPF should be used in conjunction with other security measures such as DKIM (DomainKeys Identified Mail) and DMARC (Domain-based Message Authentication, Reporting, and Conformance). SPF while an important component of a comprehensive email security strategy should be combined with more sophisticated advanced phishing protections and user education.

Move Beyond SPF with IRONSCALES

Combining SPF, DKIM, and DMARC with a comprehensive email security solution like IRONSCALES™ is the best way to ensure the highest level of protection against phishing attacks. IRONSCALES is a self-learning, AI-driven email security platform that continuously detects and remediates advanced threats like spoofing, impersonation Business Email Compromise (BEC), credential harvesting, Account Takeover (ATO), and more, in milliseconds. Together SPF and IRONSCALES ensure complete protection for your organization against advanced phishing attacks.

Check out the complete IRONSCALES email security solution here.