Which email validation protocol is used by domain owners for preventing email spoofing?

The Sender Policy Framework (SPF) is a crucial email validation protocol designed to help domain owners prevent email spoofing. It works by allowing domain owners to specify which mail servers are authorized to send emails on behalf of their domain. This is accomplished through DNS (Domain Name System) records that outline the IP addresses of authorized mail servers. When an email is received, the receiving server checks the SPF record of the sending domain to verify if the email is sent from an allowed server. If the sending server's IP address is not listed in the SPF record, the email can be marked as spam or rejected altogether, thereby reducing the risk of phishing attacks and ensuring that recipients can trust the source of their emails.

In this context, tools like MxToolbox and Email dossier serve different purposes, primarily focusing on email diagnostics and analytics rather than validation protocols to prevent spoofing. NetCraft offers insights more related to internet security and web presence than email authentication. Therefore, they do not apply directly to the mechanism and functionality provided by SPF in mitigating email spoofing.