Summary
When sending emails through platforms like Iterable that leverage Amazon SES shared infrastructure, email senders often encounter challenges with SPF alignment and DMARC compliance. These issues primarily stem from the default configuration where the Return-Path (MAILFROM) domain does not align with the From header domain, leading to SPF authentication failures in diagnostic tools. Despite these warnings, DMARC compliance is often maintained due to DKIM (DomainKeys Identified Mail) alignment, which is typically configured and aligned correctly by these services.
Key findings
- Default setup: Iterable, when using Amazon SES shared infrastructure, typically does not provide SPF alignment by default for the 'From' header domain.
- Return-path domain: The return-path (MAILFROM) domain often remains as uniquestring@amazonses.com, preventing SPF alignment with your sending domain.
- DKIM alignment: DMARC compliance is usually achieved through DKIM alignment, as both Iterable and Amazon SES facilitate setting up custom DKIM signatures.
- Tool discrepancies: Some deliverability tools may report SPF authentication errors due to this lack of alignment, even if DMARC passes via DKIM.
- Redundancy: While not strictly necessary for DMARC to pass, achieving SPF alignment provides an additional layer of authentication, often referred to as a belt and suspenders approach.
Key considerations
- DMARC passing: If DKIM is aligned and DMARC passes, the lack of SPF alignment is generally not a critical deliverability issue.
- Custom MAILFROM: Amazon SES allows for a custom MAIL FROM domain, which can enable SPF alignment, but this requires specific configuration by the email service provider (ESP) or a dedicated setup.
- Dedicated infrastructure: Achieving full SPF alignment often necessitates moving to dedicated IP addresses or specific dedicated configurations within the ESP, which can involve additional complexity, such as IP warming.
- Monitoring: Regularly monitor your DMARC reports to ensure continuous compliance through DKIM, even if SPF does not align.
- Email authentication standards: Understand how SPF, DKIM, and DMARC interact to ensure optimal email deliverability.
What email marketers say
Email marketers using shared infrastructure with services like Iterable and Amazon SES frequently report seeing SPF non-alignment issues in their deliverability reports. While acknowledging the desire for all green checks, many find that DMARC compliance is still achieved through DKIM. The general consensus is that custom SPF alignment via a custom MAILFROM domain is desirable but often not offered by default on shared pools and may require a shift to dedicated sending infrastructure, which presents its own set of challenges, particularly for high-volume senders.
Key opinions
- SPF alignment limitation: Marketers frequently report that Iterable, despite using SES, does not support SPF alignment with the 'From' address by default on shared infrastructure.
- DKIM sufficiency: Many marketers note that DMARC compliance is adequately met through DKIM alignment in this scenario.
- Reporting discrepancies: Some tools show SPF non-alignment errors, leading to marketer concern, even when DMARC passes.
- Custom MAILFROM challenge: There's a desire for a custom MAILFROM domain to achieve SPF alignment, but it's often not readily available or requires significant platform changes.
- Dedicated server implications: Marketers are sometimes advised to move to dedicated servers for SPF alignment, which can be complex due to warm-up processes and ongoing management.
Key considerations
- Deliverability impact: Marketers should assess if the SPF non-alignment genuinely affects their inbox placement or if DKIM alignment sufficiently maintains deliverability.
- Tool interpretation: It is important to understand what deliverability tools are actually measuring and whether an SPF error is critical if DMARC passes.
- Platform capabilities: Marketers should clarify with their ESP (Iterable) whether a custom MAILFROM domain is an option for their shared infrastructure or if it requires a dedicated setup. Understanding this limitation is key.
- Cost-benefit analysis: Evaluate the benefits of achieving SPF alignment through dedicated infrastructure versus the added costs and operational complexities involved.
- SPF alignment importance: Recognize that while SPF non-alignment can be concerning, DKIM alignment often carries more weight for DMARC compliance.
Marketer view
Email marketer from Email Geeks notes that their deliverability tools, including Google Postmaster Tools, are consistently reporting SPF not present/authenticated errors, despite explanations that SPF is handled via CNAME records. They are looking for ways to achieve an all green status.
Marketer view
Email marketer from Email Geeks shares that during a recent interaction with Iterable, it was confirmed that their system, while functioning on SES infrastructure, does not natively provide SPF alignment (setting up MAILFROM) to match the 'From' address. Consequently, only DKIM alignment is achievable for DMARC compliance.
What the experts say
Deliverability experts generally concur that a lack of SPF alignment on shared infrastructure, while generating warnings in some testing tools, is often not detrimental to DMARC compliance, provided DKIM alignment is correctly configured. They advise that DMARC can pass if either SPF or DKIM aligns, making DKIM the primary fallback for shared pools. However, they also stress that achieving full SPF alignment (belt and suspenders) offers enhanced redundancy and is a valuable long-term goal to mitigate future deliverability risks, even if it requires more effort.
Key opinions
- Normal for shared: Experts confirm that SPF non-alignment is a normal occurrence on shared email infrastructure and typically does not cause harm if DKIM aligns.
- DKIM's role: DMARC passing primarily relies on DKIM alignment in shared environments where SPF may not align due to the return-path domain.
- Redundancy benefit: While not immediately critical, achieving both SPF and DKIM alignment (belt and suspenders) is a recommended long-term strategy for greater email authentication robustness.
- Future risk mitigation: Having both authentication methods aligned minimizes the risk of DMARC failure if one (e.g., DKIM) experiences issues.
- Return path importance: The alignment between the Return-Path (envelope from) and the sending domain is expected and crucial for SPF to pass DMARC.
Key considerations
- Prioritize DKIM: For shared infrastructure, ensure DKIM is meticulously set up and consistently passing DMARC to maintain deliverability.
- Understand reporting: Do not panic over SPF warnings if DMARC reports show successful authentication via DKIM. Understand the nuances of DMARC alignment.
- Long-term goal: Consider pursuing SPF alignment with a custom MAILFROM domain as a strategic enhancement, even if it's not an immediate critical fix.
- Evaluate dedicated options: If complete SPF control is a high priority, research the feasibility and impact of transitioning to dedicated sending infrastructure. AWS provides guidance on DMARC compliance.
- Monitor deliverability: Continuously monitor email deliverability metrics to detect any impact from SPF non-alignment, even if DMARC is passing.
Expert view
Deliverability expert from Email Geeks, who built KBXSCORE, confirms that SPF does not align as reported by users. They clarify that the report indicates DMARC is passing because each brand has a first-party DKIM signature, meaning DMARC passes based on DKIM alignment, rather than SPF.
Expert view
Deliverability expert from Email Geeks states that a lack of SPF alignment on shared infrastructure is quite normal. They add that while it might be frustrating to see errors or warnings in reporting tools, it's likely not causing any actual harm to deliverability.
What the documentation says
Official documentation from Amazon SES, Iterable, and DMARC resources clarifies the mechanisms of SPF, DKIM, and DMARC in the context of shared infrastructure. It is stated that DMARC can pass via either SPF or DKIM, with a common configuration for shared services involving strict DKIM alignment and relaxed SPF alignment, or SPF alignment being absent due to the use of a default return-path domain (e.g., amazonses.com). While Amazon SES supports custom MAILFROM domains for SPF alignment, this is an advanced configuration that ESPs built on SES may or may not expose to their users on shared pools.
Key findings
- DMARC flexibility: DMARC allows compliance if either SPF or DKIM aligns with the 'From' header domain.
- SES SPF alignment: Amazon SES supports relaxed SPF alignment, meaning the Return-Path domain only needs to share an organizational domain with the 'From' header domain.
- Custom MAILFROM: Amazon SES offers the ability to configure a custom MAILFROM (Return-Path) domain, enabling strict SPF alignment with your 'From' header domain.
- Iterable setup: Iterable provides instructions for DNS record updates to enable SPF and DKIM authentication.
- Alignment types: Documentation outlines that without a custom MAIL FROM domain, SPF alignment often fails because the 'envelope from' (Return-Path) and 'header from' values are different organizational domains.
Key considerations
- Default shared behavior: It is important to recognize that SPF non-alignment is a common characteristic of shared sending pools unless a specific custom MAILFROM setup is utilized.
- Platform limitations: While underlying services like Amazon SES support advanced features like custom MAILFROM, the ESPs built on them (e.g., Iterable) may not expose these options to users on shared plans.
- DMARC configuration: Focus on ensuring your DMARC record and policy are correctly implemented and that DKIM is robustly configured to pass DMARC.
- Monitoring DMARC reports: Utilize DMARC reports to verify that emails are indeed passing DMARC via DKIM alignment, even if SPF alignment is absent. Understanding these reports is critical.
Technical article
Documentation from DMARC.wiki states that Amazon SES supports DMARC compliance through both SPF and DKIM. It specifies that SES enforces strict alignment on DKIM but only relaxed alignment on SPF, which means the envelope sender domain needs to share an organizational domain with the 'From' header for SPF to pass DMARC.
Technical article
Documentation from MailBluster clarifies that without a custom MAIL FROM domain, DMARC can only align with DKIM but not with SPF. This is because the 'envelope from' (Return-Path) and 'header from' values will not be the same, preventing SPF from passing alignment checks.
Related resources
6 resources
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