How do I align SPF authentication with my sending domain in Google Postmaster Tools?

Key findings

• SPF passes, but not aligned: An email might successfully pass SPF authentication, but if the domain used for SPF checking (the smtp.mailfrom or Return-Path) does not align with the From header, GPT will not attribute that SPF pass to your primary sending domain.
• Data discrepancies in GPT: Google Postmaster Tools only displays data for domains that are properly authenticated and align with the From header of your outgoing emails. If your smtp.mailfrom domain is different from your From domain, GPT might show no data for your intended domain.
• Role of ESPs: Many email service providers (ESPs) use their own tracking or bounce domains for the Return-Path. This can lead to SPF passing on the ESP's domain, but failing alignment with your primary From domain in GPT.
• Impact on DMARC: SPF alignment is a critical component of DMARC. If SPF fails alignment, DMARC will only pass if DKIM alignment is successful. You can learn more about this in our simple guide to DMARC, SPF, and DKIM.

Key considerations

• Custom SPF domains: Ensure your ESP configures SPF to use your custom domain (or a subdomain) as the Return-Path or Mailfrom domain. This allows for SPF alignment with your From header.
• DKIM alignment: If SPF alignment is challenging, focus on ensuring your DKIM signature's d= tag matches or is a subdomain of your From header. This is often easier for ESPs to implement. For more insights, refer to this guide on SPF records.
• Google Postmaster Tools registration: Register the exact domain you are looking for data on (the From domain) in Google Postmaster Tools. This involves publishing a DNS TXT record to verify domain ownership. Our guide on ultimate guide to Google Postmaster Tools V2 provides a detailed walkthrough.

Key opinions

• Conflicting data points: Many marketers find it confusing when SPF passes according to email headers, but Google Postmaster Tools (GPT) shows no or low SPF authentication rates for their From domain, indicating a misunderstanding of alignment.
• Overlooking alignment details: There's a tendency to overlook the subtle differences between SPF passing and SPF alignment, which is crucial for GPT to report on your specific domain.
• ESP role in SPF: Marketers often rely on their ESP to handle SPF, sometimes without realizing that ESPs may use their own domains for Return-Path, leading to misalignment. Our article on authenticating email with your own domain versus an ESP's delves deeper into this.

Key considerations

• Verifying headers: It is essential to examine email headers to understand which domains are being used for SPF and DKIM authentication (the Return-Path and DKIM's d= domain) versus your visible From domain.
• Engaging ESP support: Marketers should communicate with their ESPs to ensure that SPF is configured to align with their primary sending domain, possibly by using a custom Return-Path or Mailfrom domain.
• Understanding DMARC impact: While SPF passing is good, SPF alignment is essential for DMARC to pass SPF checks. Without alignment, DMARC will rely solely on DKIM alignment, as highlighted by Iterable's insights on Google Postmaster Tools.
• Continuous monitoring: Regularly checking Google Postmaster Tools and understanding email headers helps marketers proactively identify and resolve alignment issues to ensure consistent deliverability.

Key opinions

• IP inclusion in SPF: Experts clarify that IPs are not always necessary in SPF records; the focus should be on including the sending sources of the 5321.From domain (Return-Path). Excessive DNS lookups (beyond 10) can cause issues.
• No authentication connection: If the domain you are monitoring in GPT doesn't match the domains used for SPF or DKIM authentication in the email headers, GPT will not display data for your monitored domain. This is a common root cause of confusion.
• Understanding header domains: It is vital to distinguish between the 5321.From (Return-Path), DKIM signing domain (d=), and 5322.From (visible From) domains, as each plays a specific role in authentication and alignment. Our guide on how to verify DMARC, DKIM, and SPF setup helps with this.

Key considerations

• Aligning d= for DKIM: The simplest solution is often to request your ESP to sign DKIM with your main sending domain (or a subdomain), ensuring DKIM alignment, which is generally easier to control than SPF alignment.
• Registering correct domains in GPT: Ensure that the domain you register and expect to see data for in Google Postmaster Tools is the one that is actually aligning for SPF or DKIM. If your Return-Path domain is different from your From domain, you'll need to register both if you want to see data for both in GPT.
• DMARC considerations: Achieving SPF alignment is ideal, but for DMARC to pass, only one of SPF or DKIM needs to align. If SPF alignment is not feasible, strong DKIM alignment becomes even more critical. Mailjet's article on GPT elaborates on DMARC reporting.

Key findings

• SPF authentication fundamentals: SPF (Sender Policy Framework) authenticates emails by verifying the sending IP address against a list of authorized IPs in the sender's DNS record. This check is performed on the Mailfrom domain.
• Alignment for GPT reporting: Google Postmaster Tools specifically looks for alignment between the Mailfrom domain and the From header domain to populate its SPF dashboard data for your chosen domain.
• DMARC's dependency on alignment: DMARC (Domain-based Message Authentication, Reporting, and Conformance) requires either SPF or DKIM to be aligned with the From header. If SPF doesn't align, DMARC relies solely on DKIM for its pass/fail determination.

Key considerations

• DNS records for verification: To register and verify your domain in Google Postmaster Tools, you'll need to add specific TXT records to your domain's DNS settings. This verifies ownership and allows Google to collect data for that domain.
• Configuring ESPs for alignment: When using an Email Service Provider, ensure their configuration allows for SPF authentication using your own domain (or a subdomain) in the Return-Path to achieve alignment with your From header.
• Monitoring DMARC reports: DMARC reports provide detailed insights into your SPF and DKIM authentication and alignment rates, which can help in diagnosing issues that might not be immediately apparent in GPT's summary view. AutoSPF's guide provides a detailed setup for Google SPF records.