Why is SPF failing in SFMC even though it appears to pass, and how do I fix it?
Summary
What email marketers say9Marketer opinions
Email marketer from Stackoverflow explains that a common reason for SPF failing is not including the proper include statement, especially for third-party senders like SFMC. They said to make sure `include:mc.spf.salesforce.com` is added to your SPF record.
Email marketer from Mailjet shares that SPF alignment issues can cause SPF to appear to pass while failing DMARC checks. This occurs when the 'Mail From' domain (Return-Path) doesn't match the 'From' domain. They suggest ensuring both domains are aligned for proper authentication.
Email marketer from Reddit notes that issues can arise if the bounce domain (Return-Path) is not correctly configured or aligned with the sending domain. The user says it can lead to SPF failures even if the initial SPF check appears to pass. They recommends checking the Return-Path and ensuring it's properly set up.
Email marketer from Gmass shares to test your SPF record, and they provided instructions on how to test your SPF record is correctly setup by using tools such as `mail-tester.com` to identify issues with your SPF configuration.
Email marketer from Neil Patel explains that SPF failing despite appearing to pass could be due to incorrect SPF record syntax. He advises ensuring the SPF record is correctly formatted and includes all necessary authorized sending sources.
Email marketer from EmailGeeks says that if SenderID is failing, that could make it seem like SPF is failing. The user suggests deprecating SenderID in favour of SPF.
Email marketer from Litmus provides an overview of SPF and says it's a DNS record that lists the mail servers authorized to send emails on behalf of your domain. They said it's a first step for authentication, and without it, emails are more likely to be marked as spam.
Email marketer from Email Geeks agrees with Matt V, stating domain alignment issues are common, especially with Gmail's new requirements, causing discrepancies between old and new postmaster tools.
Email marketer from GlockApps shares that an SPF record can fail if it exceeds the limit of 10 DNS lookups. They suggest to flatten your SPF record by replacing nested `include` statements with the actual IP addresses or hostnames.
What the experts say4Expert opinions
Expert from Email Geeks suggests it could be an unaligned pass, where SPF passes on the SFMC email sender but not the aligned client domain.
Expert from Spam Resource, John Levine, explains that one common mistake that leads to SPF failing even when it appears correct is having multiple SPF records. He said to ensure there is only one SPF record for the domain, and to combine multiple directives into a single record.
Expert from Email Geeks explains potential failure points related to different MIDs and IPs, and suggests verifying subdomain SPF alignment due to SFMC's custom domain setup. He also suspects a disconnect between subdomain and top-level domain SPF records.
Expert from Word to the Wise, Laura Atkins, explains that when diagnosing SPF failures, it is essential to test the setup thoroughly using tools that simulate real-world email delivery scenarios, which help identify issues not apparent in simple record checks.
What the documentation says4Technical articles
Documentation from SFMC explains the Sender Authentication Package (SAP) and how it brands your emails. It outlines the different components, including setting up a private domain for branding and a separate domain for bounces. This source provides the steps to properly authenticate your sending domain.
Documentation from RFC explains that SPF relies on the 'MAIL FROM' address, also known as the envelope sender or Return-Path. It says that this address is often different from the 'From:' header address, which users see.
Documentation from Salesforce Help explains that SPF failures in SFMC can occur if the sending domain's SPF record doesn't include Salesforce's sending IPs or if there are multiple SPF records. It details how to properly configure SPF records to authorize Salesforce as a sending source.
Documentation from DMARC.org explains that SPF alone is often insufficient because it doesn't always protect the 'From' address seen by recipients. The documentation says that DMARC builds upon SPF and DKIM to provide stronger authentication, and alignment is key.