Sender Policy Framework, or SPF, is one of the most commonly used standards for email authentication. Implementing SPF can boost your domain safety against spoofers, but it has certain limitations when used in isolation without DKIM and DMARC.
Advantages
Stops phishing attacks
SPF authenticates your email so that when an attacker tries to send fake email from your domain, the receiving email server sees that it’s from a malicious source, and flags it.
Boosts your domain reputation
When you implement SPF, you’re signaling to email providers that you’re committed to preventing email-borne cyberattacks, making it more likely that genuine emails from your domain reach their destination inboxes instead of being falsely flagged.
Disadvantages
Forwarded emails fail authentication
When someone else forwards an email sent from your domain, their IP address won’t be listed on your SPF record. The receiving email server sees this and mistakenly flags it and the email fails SPF.
Difficulty maintaining SPF records
Domain owners often require authorized third party vendors to send emails from their domain. This means the SPF records would have to be constantly updated every time there’s a change in IP address or third party vendors.
Most users don’t see who’s really sending the email
SPF authentication happens on the specific Return-Path/mailfrom domain, not the From address that most users usually see. This means that an attacker could just send the email from a domain they control but use a different sender address. An average user wouldn’t bother to check the Return-Path/mailfrom, opening themselves up for a phishing attack.
Limit of 10 DNS lookups for SPF records
Each SPF record allows for 10 DNS lookups. If your SPF record exceeds this limit, receiving servers automatically fail SPF authentication.
PowerDMARC features a unique new tool, PowerSPF, which lets you optimize and simplify your SPF record to stay under the limit, and in just one click.
SPF by itself is limited in how effectively it stops domain spoofing, but when combined with DKIM and DMARC technology, you get robust anti-spoofing protection.