Summary

This article addresses issues with inbound SPF failures, explaining why they occur and how to resolve them effectively based on the user's role—whether sender or recipient.

Objective

To guide users in understanding SPF failures and provide actionable steps to resolve email deliverability issues caused by incorrect SPF configurations.

Introduction

SPF (Sender Policy Framework) is an email authentication mechanism that helps prevent spoofing by validating the IP addresses authorized to send emails for a domain. When an inbound email fails SPF checks, it is often due to a misconfiguration in the sender’s email system.

For instance, an error such as:

1.2.3.4 does not pass SPF checks for example.com

indicates that the sending server (1.2.3.4) is not authorized to send emails on behalf of the domain example.com as per the domain’s SPF settings.

Prerequisites

  • Access to the domain's DNS settings (for senders).
  • Knowledge of the failing email server's IP address.
  • Tools to validate SPF configurations (e.g., Kitterman's SPF Validator).

Step-by-Step Instructions

  1. Identify the Problem:
    • Determine if you are the sender or the recipient of the email flagged for SPF failure.
  2. If You Are the Sender:
    • Contact your IT administrator to review and adjust your domain’s SPF record.
    • Ensure that all IP addresses used to send emails for your domain are included in the SPF record.
    • Use