Why are marketing emails going to Gmail spam despite passing authentication checks?

Key findings

• Authentication sufficiency: Passing SPF, DKIM, and DMARC is necessary but not sufficient for inbox placement, especially with Gmail. These protocols verify sender identity but do not guarantee deliverability if other negative signals are present.
• Domain reputation: Gmail heavily relies on domain and IP reputation. A poor reputation, even if Google Postmaster Tools (GPT) dashboards initially appear green, can be the root cause. This often requires digging into historical GPT data for accurate insights (see ultimate guide to Google Postmaster Tools).
• Engagement metrics: Low open rates (e.g., 5% or less), high bounces, and zero spam complaints (which can indicate messages are not reaching the inbox at all) are strong indicators of spam folder delivery.
• Recipient behavior: Recipients marking emails as spam, even if not explicitly clicking a spam button (implicit complaints), heavily influence deliverability. Lack of engagement also signals disinterest to mailbox providers.
• Content and setup: Issues like email clipping, non-compliant HTML, or using a sending domain that differs significantly from the sign-up website can contribute to spam placement.
• New sender challenges: New domains or those not previously in active use often start with a neutral or poor reputation, leading to spam folder placement from day one, even with low sending volumes.

Key considerations

• Holistic review: Beyond technical authentication, review your entire email program: list acquisition, content relevance, sending frequency, and recipient engagement. See why your emails go to spam.
• Engagement-based sending: Prioritize sending to highly engaged subscribers, especially when attempting to recover a low domain reputation. This can positively influence deliverability over time.
• Google Postmaster Tools deep dive: While GPT dashboards may look good, check historical data for specific metrics like IP and domain reputation, as well as any rejection reasons. For more on this, read how to troubleshoot Gmail emails landing in spam.
• Content optimization: Ensure your email content is relevant, provides value, avoids spam trigger words, and follows HTML best practices to prevent clipping or filter triggers.
• Feedback loops: If possible, utilize feedback loops to identify and remove recipients who mark your emails as spam, even if GPT shows zero complaints.

Key opinions

• Low open rates: A common observation is very low open rates (e.g., 5% or less), particularly for Gmail recipients, even when other domains show better performance. This strongly suggests emails are not reaching the primary inbox.
• GPT reputation mismatch: Marketers note that Google Postmaster Tools (GPT) might display a 'green' or 'compliant' dashboard, yet deeper dives into historical data reveal a 'bad' domain reputation, indicating an initial or ongoing issue with Gmail's filtering.
• Zero complaint rate paradox: A zero spam complaint rate in GPT, while seemingly positive, is often interpreted by marketers as evidence that emails are going straight to spam, preventing users from even seeing or marking them as spam.
• New domain challenges: Starting to send from a domain that has existed but was not previously in active use can effectively make it a 'new' domain in the eyes of ISPs, triggering spam filters from the outset.
• Engagement as a metric: Successful engagement (clicks, opens) with the few emails that do land in the inbox can be a positive sign, indicating that if the email reaches the user, the content is relevant. This can be a lever for reputation improvement.
• Opt-in quality: Even with opt-in checkboxes, the perceived optionality of consent, or a mismatch between sign-up expectation and email content, can lead to poor engagement or spam reports.

Key considerations

• Auditing user experience: Marketers should audit their sign-up process and initial email experience. Does the opt-in feel truly optional? Does the email content align with user expectations formed during sign-up? This relates to how to determine if marketing emails are going to spam.
• Leveraging engaged users: When domain reputation is low, focusing sends on segments known to engage can help rebuild trust with mailbox providers, as positive interactions signal desired mail. This is key to why marketing emails move to spam.
• Monitoring content clipping: Ensure emails are not being clipped (truncated) by email clients, which can negatively impact user experience and engagement.
• Email sending domain consistency: If emails come from a domain completely different from where users signed up, it can increase confusion and lead to spam complaints, even if explicit permissions exist. Refer to Mailchimp's guide to avoiding spam filters.
• Long-term commitment: Improving domain reputation and inbox placement can take time, ranging from days to months, depending on the severity of the initial problem.

Key opinions

• Beyond authentication: Experts confirm that passing SPF, DKIM, and DMARC only verifies the sender's identity, it doesn't guarantee inbox delivery. Other factors related to sender behavior and reputation are paramount.
• Reputation from day one: A domain can start with a poor reputation from its very first send if it's perceived as new or if there are issues with its history or the IPs it inherited, regardless of sending volume.
• Engagement is key: Positive engagement from recipients (opens, clicks) is crucial for building and maintaining a good sender reputation, especially for newer domains or those trying to recover from poor standing.
• Complaint rate meaning: A zero complaint rate in Google Postmaster Tools can actually be a negative signal, indicating that emails are not even reaching the inbox for users to register complaints.
• Domain separation issues: Sending marketing emails from a domain distinct from where a user signed up can lead to confusion and increased spam complaints, as recipients may not recognize the sender.
• Volume is not the only factor: For low sending volumes (e.g., 80-150 emails/day), IP warming is typically not the primary issue. The problem likely lies in other reputation or content factors.

Key considerations

• Sender reputation recovery: Recovering a poor domain reputation can take anywhere from days to months, requiring sustained positive sending behavior and engagement. Read more about improving domain reputation using Google Postmaster Tools.
• List hygiene and permission: Even with opt-ins, ensuring clear user consent and regularly cleaning your list of unengaged subscribers or spam traps is vital. This is especially true for transactional emails that may be landing in spam (see why transactional emails go to spam).
• Deep diagnostics: For complex cases, providing specific email examples or allowing experts to sign up for the email flow can yield more precise diagnoses than generic advice.
• Tracked links investigation: While native shorteners like YouTube's aren't usually problematic, the ESP's click tracking domain wrapping those links should be investigated for its reputation.
• Holistic view of domain usage: Consider if a domain only sending to new subscribers (who are often 'wild cards' in terms of engagement) might struggle more than one used for both new and engaged, tried-and-true subscribers.

Key findings

• Authentication purpose: Email authentication protocols like SPF, DKIM, and DMARC are designed to verify the sender's identity and prevent phishing or spoofing, not solely to ensure inbox delivery. They are a baseline requirement for trust.
• Sender reputation weighting: Mailbox providers heavily weigh sender reputation, which is influenced by factors such as spam complaint rates, bounce rates, recipient engagement (opens, clicks, replies), and whether users move emails from spam to inbox.
• Content and design: The content and HTML structure of an email are critical. Spam trigger words, broken HTML, or overly image-heavy emails without text alternatives can lead to spam folder placement.
• List quality and consent: Maintaining a clean and permission-based email list (using double opt-in where possible) is crucial to avoid spam traps and reduce complaints.
• DMARC policy impact: A strong DMARC policy (p=quarantine or p=reject) helps protect your domain from abuse but requires careful implementation to avoid legitimate emails being blocked (learn more from Klaviyo's DMARC guide).

Key considerations

• Compliance with regulations: Ensure your email program complies with anti-spam laws like CAN-SPAM (in the US) or GDPR (in Europe), which include requirements for clear identification, valid headers, and an easy unsubscribe mechanism. More details in Twilio's tips to keep emails out of spam.
• Monitoring deliverability metrics: Utilize tools like Google Postmaster Tools to monitor your domain and IP reputation, spam rate, feedback loop data, and authentication results comprehensively.
• Sender best practices: Beyond technical setup, adhere to general sender best practices such as sending relevant content, segmenting lists, and managing sending frequency to optimize engagement. For a complete overview, check our simple guide to DMARC, SPF, and DKIM.
• Address bounce management: Promptly remove hard bounces from your lists and investigate soft bounces to maintain list health and improve deliverability.
• User feedback incorporation: Actively seek and incorporate user feedback to ensure your email program meets recipient expectations and preferences, reducing the likelihood of being marked as spam.