How to troubleshoot SPF failures in Google Postmaster Tools and improve email delivery?
Summary
What email marketers say9Marketer opinions
Email marketer from EasyDMARC shares using tools to test your SPF record. These tools can validate the syntax, check for errors, and ensure proper configuration. They can also help identify if you're exceeding the DNS lookup limit.
Email marketer from Reddit explains that SPF failures in Google Postmaster Tools often occur when emails are forwarded. The forwarder's server isn't authorized by your SPF record, causing the check to fail.
Email marketer from Reddit shares to check the Return-Path of your emails. ESPs often use their own Return-Path domains for tracking, which can cause SPF failures if your DMARC policy is strict. Aligning DKIM can mitigate this.
Email marketer from EmailToolTester shares that ensuring your SPF record is up-to-date with all sending sources is critical, especially when using multiple ESPs or sending from different servers. Also, using a tool to monitor DMARC reports helps catch SPF failures.
Email marketer from SparkPost explains that common SPF errors include incorrect syntax, exceeding the DNS lookup limit, and failing to include all authorized sending sources (e.g., ESPs, internal servers).
Email marketer from MailerLite shares that SPF prevents spammers from sending messages with your domain. Having a valid SPF record ensures that your emails aren't marked as spam.
Email marketer from GlockApps shares to use a deliverability testing tool such as GlockApps to check SPF, DKIM and DMARC records, and if they are passing properly.
Email marketer from Email Marketing Forum responds that sometimes Google Postmaster Tools might show SPF failures due to caching issues or delays in DNS propagation. Double-check after a few days to see if the issue persists.
Email marketer from Mailjet shares that to troubleshoot SPF failures, verify your SPF record syntax, ensure all sending sources are included, and that you haven't exceeded the 10 DNS lookup limit.
What the experts say9Expert opinions
Expert from Spamresource.com responds that ensure that all mail servers sending on behalf of your domain are authorized in your SPF record. This includes third-party senders, ESPs, and any internal servers. In Google Postmaster Tools, you can check the Authentication section to see which IPs are failing SPF checks. Add these authorized IPs/domains to your SPF record.
Expert from Email Geeks explains that Google Postmaster Tools showing SPF failures doesn't necessarily mean SPF is failing. It could be because the SPF domain is owned by the ESP, and the user doesn't have permission to see that data for that domain.
Expert from Email Geeks shares that Google Postmaster Tools can be confusing. Users often add their sending domain but Gmail primarily shows results for the authenticated domain (return-path). Thus, if the return path isn't the same domain, Google can't show SPF pass or fail.
Expert from Word to the Wise explains that SPF records have a limit of 10 DNS lookups. If your SPF record exceeds this limit, it can cause SPF failures. To address this, minimize the number of include statements in your record, and flatten SPF records to reduce the number of DNS queries during SPF authentication.
Expert from Email Geeks suggests making sure rDNS is set up to get under the SpamAssassin threshold.
Expert from Email Geeks explains that misaligned SPF with DMARC is only a problem if the DMARC record has a 'p=reject' policy and there's no aligned DKIM signature due to a missing valid signature or forwarding breaking DKIM. Rejections due to DMARC policy should appear in logs and DMARC reports.
Expert from Email Geeks explains that if more than 1% of emails are failing with timeouts, mailbox full, or unavailable errors, data quality should be examined to ensure only opt-in mail is sent, because mailbox unavailable means bad email addresses are present.
Expert from Email Geeks explains that using CSS to hide content on mobile/desktop with `font-size: 0px` will trigger FONT_INVIS. Laura Atkins adds that SpamAssassin is not widely used, so it's likely not the root of the problem.
Expert from Email Geeks clarifies that no rDNS is a misconfiguration of a sending IP address, unrelated to authentication. _FONT_INVIS_NORDNS_ means that invisible font is present (foreground and background font are the same) and there is no rDNS. Reverse DNS can be checked using `dig -x IPAddress`.
What the documentation says5Technical articles
Documentation from DMARC.org explains that for SPF to work with DMARC, SPF alignment is needed. This requires the domain in the 'Return-Path' (also known as 'Mail From') to match the domain in the 'From' header. If it doesn't align, DMARC may fail.
Documentation from Google Workspace Admin Help explains that SPF authenticates the sending mail server. When SPF passes, it confirms that the server is authorized to send emails on behalf of your domain. Failures can lead to deliverability issues.
Documentation from Valimail explains to ensure your SPF record stays below the limit of 10 DNS lookups. To avoid exceeding the limit, flatten SPF records to reduce the number of lookups.
Documentation from RFC explains the importance of the proper SPF syntax. The most common syntax uses an `include:` mechanism to use ESP SPF records.
Documentation from Microsoft explains that using SPF, DKIM and DMARC together can help prevent spoofing and phishing attacks. Ensuring correct setup for each record increases deliverability.