What is the primary purpose of SPF in Email Authentication?

Sender Policy Framework (SPF) is an email authentication standard designed to prevent domain spoofing. A domain owner publishes an SPF record in their Domain Name System (DNS) as a TXT record. This record contains a list of IP addresses and mail servers that are explicitly authorized to send email on behalf of that domain. When an inbound mail server receives a message, it performs a DNS lookup for the SPF record of the domain in the MAIL FROM address. It then compares the IP address of the sending mail server with the authorized list in the SPF record. A match indicates the message is from a legitimate source, passing the SPF check.

A. SPF authenticates the sending server's IP address, not the recipient's authorization to receive an email.

C. This describes DomainKeys Identified Mail (DKIM), which uses cryptographic digital signatures to verify message integrity and authenticity.

D. This describes Domain-based Message Authentication, Reporting, and Conformance (DMARC), which uses SPF and DKIM results to enforce a policy.

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1. Internet Engineering Task Force (IETF). (April 2014). RFC 7208: Sender Policy Framework (SPF) for Authorizing Use of Domains in Email

Version 1. Section 1

Introduction

Paragraph 1. "Sender Policy Framework (SPF) is an email validation system designed to prevent email spam by detecting email spoofing

a common vulnerability

by verifying sender IP addresses."

2. Proofpoint

Inc. (n.d.). What is Sender Policy Framework (SPF)? Proofpoint Official Documentation. "SPF is an email authentication protocol that allows the owner of a domain to specify which mail servers they use to send mail from that domain." and "The receiving email server checks the SPF record to verify that the mail is coming from an authorized server..."

3. D. J. Bernstein. (2006). Sender Policy Framework. In Internet Measurement Conference (IMC '06). Association for Computing Machinery

New York

NY

USA

353–358. Section 1

Introduction. "SPF allows a domain to publish a list of its mail servers. A mail receiver can check whether an incoming mail message originated at one of those servers." DOI: https://doi.org/10.1145/1177080.1177125