Summary
Even when emails sent via an HR system connected to Gmail successfully pass authentication checks like SPF, DKIM, and DMARC, they can still consistently land in spam folders. This occurs because Gmail's sophisticated spam detection system evaluates a multitude of signals beyond basic authentication. Primary factors include the sender's overall reputation, which is built on historical sending practices, user engagement, and spam complaint rates. Issues such as the email's content-including elements like overly generic or suspicious links, problematic formatting, or the presence of spam trigger words-can also lead to filtering. Furthermore, the quality and configuration of the sending IP address, particularly the reverse DNS (rDNS) and whether it's a shared IP with other senders, play a critical role. Recipient engagement, or a lack thereof, significantly influences whether emails bypass spam filters. Ultimately, successful authentication is a foundational element, but a holistic approach to deliverability, focusing on reputation, content quality, and recipient interaction, is essential for reaching the inbox.
Key findings
- Reputation Trumps Authentication: Even with SPF, DKIM, and DMARC successfully passing, a poor sender reputation is a primary reason emails land in spam. Gmail's filters weigh factors like past sending practices, spam complaint rates, bounce rates, and recipient engagement more heavily than authentication alone.
- Holistic Spam Detection: Gmail employs a sophisticated spam detection system that considers hundreds of signals beyond basic authentication. This includes detailed content analysis, network patterns, user feedback, and the historical reputation of both the sending IP and domain.
- IP and rDNS Quality are Key: Generic reverse DNS records, especially for shared IP addresses or cloud instances, often correlate with poor sender reputations. Being on a shared IP pool with problematic senders can also negatively impact deliverability, common for third-party HR systems.
- Content and Recipient Interaction: The actual content of the email, including spam trigger words, excessive links, or poor HTML, significantly influences spam filtering. More importantly, how recipients interact with the email-low open rates, immediate deletions, or marking as spam-directly trains Gmail's filters.
- DMARC Policy Impact: While SPF and DKIM pass, a DMARC policy set to 'p=none' (monitoring only) or the absence of a strong DMARC policy gives receiving servers more leniency. Without a 'quarantine' or 'reject' policy, authenticated but otherwise suspicious emails may still be filtered to spam based on other signals.
Key considerations
- Audit HR System Configuration: Thoroughly check the HR system's email routing, ensure the 'From' address perfectly aligns with the authenticated domain, and verify that the underlying email sending service is optimized for deliverability best practices. Misconfigurations can lead to emails being flagged.
- Monitor Sender Reputation: Regularly use tools like Google Postmaster Tools to track your sender reputation. Pay close attention to IP and domain reputation, spam complaint rates, and delivery errors, as these metrics significantly influence deliverability.
- Optimize Email Content: Review email content for potential spam triggers such as excessive links, shortened URLs, incorrectly encoded characters, poor HTML, or common spam trigger words. Ensure content is personalized and relevant to recipients.
- Maintain List Hygiene & Engagement: Prioritize maintaining a clean, engaged email list by regularly removing outdated or invalid addresses. Provide a clear and easily accessible unsubscribe link. Low engagement, combined with negative actions like 'delete without opening' or spam reports, can harm deliverability.
- Configure Specific rDNS: If the HR provider uses cloud instances like AWS, they should configure their outbound mail with a specific reverse DNS, for example, 'outbound_mta.providername', and ensure the machine EHLOs with that value. Generic rDNS records often have poor reputations.
- Utilize Feedback Loops: Confirm that the email service provider used by the HR system is properly subscribed to ISP Feedback Loops, such as those provided by Gmail. This ensures real-time notifications for spam complaints, allowing for prompt removal of disengaged users.
- Manage Sending Volume & Patterns: Be mindful of sudden and uncharacteristic spikes in email sending volume or inconsistent sending patterns. Mailbox providers monitor these behaviors, and unusual activity can raise red flags regardless of authentication.
- Investigate Header Differences: Compare the headers of emails that deliver successfully versus those that go to spam. This can reveal subtle differences in routing, settings, or other factors influencing deliverability.
What email marketers say
9 marketer opinions
While technical authentication like SPF, DKIM, and DMARC is a fundamental step, emails from HR systems often land in spam because deliverability extends far beyond these basic checks. The core issue frequently lies in the sender's overarching reputation, which is influenced by historical sending practices, user engagement, and complaint rates, not just passing authentication. Factors like the content's quality, relevance, and personalization; the state of the email list; the sending volume and patterns; and critical behind-the-scenes configurations of the HR system itself, all contribute to Gmail's decision-making process. Even if technically sound, emails are filtered based on a complex interplay of user perception, engagement signals, and the overall health of the sending infrastructure, including shared IP pools and integration with feedback loops.
Key opinions
- Sender Reputation Beyond Authentication: While authentication passes, a poor sender reputation for the sending IP address or domain is a primary reason emails land in spam, influenced by previous sending practices, spam complaints, and shared IP issues.
- Content and Engagement are Critical: Email content, including spam trigger words, excessive links, or poor HTML, and how recipients interact with it (low opens, deletions, spam reports), significantly influence spam filtering, irrespective of authentication.
- List Hygiene and Complaint Rates Impact: Poor list hygiene, such as sending to outdated or invalid addresses, combined with a lack of a clear unsubscribe option, leads to high spam complaint rates, strongly signaling unwanted mail to filters.
- Sending Behavior Anomalies: Sudden, uncharacteristic spikes in sending volume or inconsistent patterns can trigger spam filters, as mailbox providers monitor for unusual activity.
- HR System Misconfigurations: Misalignments in the 'From' address, or unoptimized underlying email sending services within HR systems, can cause emails to be flagged despite passing basic authentication.
- Negative Engagement Signals: Low positive engagement (few opens, clicks) coupled with negative actions (delete without opening, report spam) signals to Gmail that messages are unwanted, leading to spam folder placement.
- Feedback Loop Importance: If the HR system's email service provider isn't subscribed to ISP Feedback Loops, they won't receive real-time spam complaints, preventing removal of disengaged users and perpetuating reputation harm.
Key considerations
- Audit HR System's Email Routing: Investigate if the HR system's email is routed through a specific email service like G Suite or is directly using the email address, and check for potential shared IP issues if it's the latter.
- Verify HR System Configuration: Ensure the 'From' address perfectly aligns with the authenticated domain and that the HR system's underlying email sending service is optimized for deliverability best practices.
- Monitor Sender Reputation Metrics: Utilize tools like Google Postmaster Tools to track IP and domain reputation, spam complaint rates, and engagement, as these are critical indicators.
- Optimize Email Content and Personalization: Review email content for spam trigger words, excessive links, and poor formatting, and focus on making messages relevant, personalized, and valuable to recipients.
- Maintain Robust List Hygiene: Regularly clean email lists to remove outdated or invalid addresses and ensure a clear, easily accessible unsubscribe link is provided to minimize spam complaints.
- Manage Sending Volume Consistency: Avoid sudden, large spikes in email sending volume and maintain consistent sending patterns to prevent triggering spam filters.
- Ensure Feedback Loop Integration: Confirm that the email service provider used by the HR system is subscribed to ISP Feedback Loops to receive prompt notifications of spam complaints and manage recipient lists accordingly.
- Address Negative Engagement: Actively monitor recipient engagement, as low opens and high rates of deletions or spam reports signal to Gmail that the messages are not valued, necessitating strategy adjustments.
Marketer view
Marketer from Email Geeks suggests checking if the HR system's email is routed through G Suite or just using the email address, advising to check for shared IP issues if it's the latter. He also speculates that the HR vendor might be experiencing issues due to Microsoft's attempts to manage marketing automation tools.
3 Mar 2022 - Email Geeks
Marketer view
Email marketer from Mailgun explains that while SPF, DKIM, and DMARC are crucial, a poor sender reputation for the sending IP address or domain is a primary reason emails land in spam. This can be influenced by previous sending practices, spam complaints, or being on a shared IP pool with problematic senders, common for HR systems using third-party providers.
15 Jun 2025 - Mailgun
What the experts say
5 expert opinions
While critical, successful SPF, DKIM, and DMARC authentication for emails sent via HR systems to Gmail often isn't enough to guarantee inbox delivery. This persistent issue stems from Gmail's advanced, multi-faceted filtering approach, which scrutinizes a broad range of signals beyond basic authentication. Key contributors to emails landing in spam include a poor sender reputation, which is influenced by historical sending patterns and recipient interactions, rather than just technical validation. Specific content elements, such as incorrectly encoded characters or the use of generic, shortened URLs, can also trigger filters. A frequently cited problem for HR systems, especially those hosted on cloud platforms like AWS, is the use of generic reverse DNS (rDNS) records. These generic IPs often carry a poor reputation due to their association with various senders, including spammers. Ultimately, deliverability hinges on a holistic blend of authentication, a robust sender reputation, and clean, well-constructed email content, all of which are continuously evaluated by sophisticated inbox providers.
Key opinions
- Generic rDNS as a Specific Culprit: A primary reason for deliverability issues, even with passing authentication, is often the use of generic reverse DNS (rDNS) for HR system IPs hosted on cloud instances like AWS, which tend to have poor reputations due to their shared usage by various senders, including spammers.
- Content Nuances Matter: Beyond general content quality, specific elements like incorrectly encoded characters or the inclusion of shared or shortened URLs (e.g., bit.ly) can negatively impact deliverability and trigger spam filters.
- Holistic Evaluation Framework: Gmail's deliverability assessment is comprehensive, built upon three core pillars: successful authentication, a strong sender reputation (driven by bounce rates, complaints, and engagement), and high-quality, relevant content.
- Header Discrepancies as Indicators: Differences in email headers between successfully delivered messages and those flagged as spam can provide critical clues about underlying routing, configuration, or content issues influencing deliverability.
- IP Reputation is Tied to Usage: The reputation of an IP address, particularly those used by shared cloud instances, is heavily influenced by the aggregate sending behavior of all entities using that IP, regardless of individual sender authentication.
Key considerations
- Configure Specific rDNS for Outbound Mail: HR providers should configure their outbound mail servers with specific reverse DNS records, for example, 'outbound_mta.providername', and ensure the sending machine EHLOs with that value, rather than relying on generic cloud rDNS.
- Scrutinize Email Content for Specific Issues: Conduct a detailed review of email content for elements that can trigger spam filters, such as incorrectly encoded characters or the inclusion of shared or shortened URLs like bit.ly.
- Analyze Email Header Differences: Systematically compare the full email headers of messages that successfully land in the inbox versus those that go to spam to identify subtle differences in routing, sending parameters, or other flags.
- Investigate Internal GSuite Configurations: Explore whether the IT department has specific GSuite configurations locked down or if other internal systems might be using similar interconnections that could negatively impact the sending reputation.
Expert view
Expert from Email Geeks asks about the email content, noting that many factors can be at play. He later confirms that SPF, DKIM, and DMARC authentication all pass for the problematic emails.
2 Jul 2021 - Email Geeks
Expert view
Expert from Email Geeks suggests checking for incorrectly encoded characters or the use of shared links/shortened URLs like bit.ly within the email content. She later identifies the likely issue as the generic rDNS for the AWS instance connecting to Gmail, explaining that such IPs often have poor reputations due to potential spamming. She advises the HR provider to configure their outbound mail with a specific rDNS (e.g., outbound_mta.providername) and ensure the machine EHLOs with that value.
16 Oct 2024 - Email Geeks
What the documentation says
4 technical articles
Receiving emails from HR systems in Gmail's spam folder, even when authentication passes, is a common issue rooted in Gmail's highly advanced and comprehensive spam detection, which extends far beyond basic SPF, DKIM, and DMARC checks. This sophisticated system meticulously evaluates hundreds of signals, including user feedback, content analysis, and especially the sender's overarching reputation, which is built from factors like IP and domain history, spam complaints, bounce rates, and engagement patterns. Additionally, a permissive DMARC policy, such as 'p=none' or its absence, can further contribute by allowing receiving servers more leeway to filter otherwise authenticated but suspicious messages based on these numerous other signals.
Key findings
- Gmail's Multi-Signal Spam Detection: Gmail's sophisticated spam detection system considers hundreds of signals for filtering emails, including user feedback, content analysis, sender reputation, and network patterns, well beyond merely passing SPF, DKIM, or DMARC authentication.
- Sender Reputation is Comprehensive: Even with successful authentication, a sender's reputation, built on a comprehensive profile including IP and domain history, spam complaints, delivery errors, and user engagement, is paramount. A poor or degraded reputation will lead to emails landing in spam.
- DMARC Policy Influences Filtering Action: While SPF and DKIM pass, a DMARC policy set to 'p=none' (monitoring only) or the absence of a strong DMARC policy allows receiving servers more leniency. This means authenticated but otherwise suspicious emails might still be filtered to spam based on other negative signals.
Key considerations
- Monitor a Full Spectrum of Reputation Metrics: Utilize tools like Google Postmaster Tools and other analytics to track all aspects of sender reputation, including IP and domain health, spam complaint rates, delivery errors, and recipient engagement. These metrics collectively dictate inbox placement.
- Evaluate and Strengthen DMARC Policy: Assess the DMARC policy for the HR system's sending domain. If it's set to 'p=none' or is absent, consider moving towards 'quarantine' or 'reject' policies, after careful monitoring, to provide clearer instructions to receiving servers on how to handle suspicious, even authenticated, emails.
- Address All Non-Authentication Signals: Implement strategies to improve deliverability by focusing on elements beyond authentication, such as proactively seeking positive user feedback, refining email content to avoid spam triggers, improving recipient engagement, and ensuring clean network patterns associated with the sending IPs.
Technical article
Documentation from Google Workspace Admin Help explains that Gmail uses a sophisticated spam detection system that considers hundreds of signals beyond standard authentication, including user feedback, content analysis, sender reputation, and network patterns. Therefore, even authenticated emails can be flagged if other factors suggest they are unwanted.
29 Oct 2022 - Google Workspace Admin Help
Technical article
Documentation from Google Postmaster Tools Help shares that even with authentication, mailbox providers like Gmail track sender reputation based on IP and domain, spam complaints, and delivery errors. Low reputation or high complaint rates, visible through these tools, can cause authenticated emails to land in spam.
11 Oct 2022 - Google Postmaster Tools Help
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