Yes, but it's crucial to understand which "From" address it authenticates. SPF (Sender Policy Framework) authenticates the domain found in the email's envelope sender, also known as the 'Mail-From', 'Return-Path', or bounce address. It does not authenticate the 'From' address that you see in your email client.
This is a common point of confusion that has significant implications for email security and DMARC alignment. Let's explore the difference and see how the process works.
Every email has two 'from' addresses. Understanding the role of each one is the key to understanding how SPF works.
The purpose of an SPF record is to create a public list of all the IP addresses that are permitted to send email on behalf of your domain. As described by Kickbox, "SPF is a list of IPs that the domain owner has publicly authorized to send on its behalf." When a receiving mail server gets an email, it performs the following check:
This distinction is critically important when you implement DMARC. DMARC requires something called 'alignment' to protect your domain from spoofing. For SPF to pass DMARC, the check must not only pass, but the domain used for the SPF check (the 'Mail-From' domain) must also match the domain in the visible 'From' header.
For example, if a spammer sends an email with a From address of ceo@yourcompany.com but uses a Mail-From address of bounces@spammerdomain.com, the SPF check will be performed against spammerdomain.com. Since the spammer controls that domain, they can make the SPF check pass. However, because spammerdomain.com does not align with yourcompany.com, the message will fail DMARC's SPF alignment check.
In conclusion, while SPF is a foundational email authentication protocol, it only verifies the authenticity of the hidden 'Mail-From' address. It is the combination of SPF, DKIM, and a DMARC policy that provides robust protection against email spoofing by ensuring the domains a user sees are the domains that have been authenticated.