SPF: What It Is and What It’s Not
Discover the benefits, limitations, and functionality of SPF
What Is SPF?
SPF, or Sender Policy Framework, is an email authentication protocol you can use to authenticate your email. Email receivers who validate the authenticity of messages will query the DNS records associated with your sending domain to obtain a list of IP addresses you have explicitly authorized as valid sending systems. SPF is in widespread use, and the standard is managed by the IETF (RFC 7208).
The Protection of SPF
When email is sent from an IP that is not listed in your SPF record by someone who is not authorized to send on your domain’s behalf, SPF allows the receiver to reject it. Your customer doesn’t receive the email and your reputation and brand stays intact.
Limitations of SPF
SPF alone is not a complete solution to email authentication. There are a few elements of the equation missing even after an email sender has fully deployed SPF.
- There is no way for a recipient system to know how much reliance they should put on the SPF results for any given email.
- SPF provides no way for email receivers to provide any feedback to the email senders.
- SPF authenticates email domains that are buried deep in the message headers and not easily visible to a typical end user.
The Solution: DMARC
Cutting-Edge Email Authentication
The limitations of protocols like SPF lead to the development of a complete email authentication solutions — DMARC. The DMARC standard is an overlay that adds three key elements of feedback, policy, and identity alignment to the already deployed SPF and DKIM framework. With DMARC, you always know that the recipient your original email, and it doesn’t require behavioral adjustments from the user.