Why are my emails landing in spam even though they pass SPF, DKIM, and DMARC?

Key findings

• Reputation is key: A history of sending unwanted mail, even if corrected, can severely damage your domain and IP reputation with ISPs, leading to spam folder placement. This is particularly true for Google's filtering algorithms.
• Low send volume: For new domains or those with very low sending volumes (common in B2B), building a positive reputation can be challenging, as there isn't enough consistent traffic to signal legitimacy.
• Content and engagement: Spammy content, poor formatting, or low recipient engagement (low opens, high deletes without opening, spam complaints) can trigger spam filters, regardless of authentication. For more on content, see this guide on why emails go to spam.
• Hidden DNS issues: Even if SPF, DKIM, and DMARC pass, other DNS record misconfigurations (like missing CERT records) can sometimes subtly impact deliverability.
• Blocklist status: While MXToolbox might not show all blocklistings, some private blocklists or real-time blackhole lists (RBLs) could still be affecting your delivery. Understanding how email blacklists work is crucial.

Key considerations

• Monitor reputation actively: Utilize tools like Google Postmaster Tools to track your domain's reputation with major ISPs. This offers insights beyond authentication metrics.
• Segment and warm up: If you have a large list or are a new sender, segment your audience and warm up your IP/domain gradually. Even for established domains, sudden volume spikes can be detrimental.
• Content review: Regularly audit your email content for spam trigger words, excessive links, poor image-to-text ratio, and inconsistent formatting. A detailed content review can uncover hidden issues.
• Engagement strategy: Focus on sending relevant, valuable emails that encourage opens and clicks. Low engagement signals to ISPs that your emails are not desired. Read our guide on troubleshooting emails landing in spam.
• Address underlying issues: If past issues, such as API abuse or large-scale spamming, have occurred, the damage to your sender reputation can persist for a long time. It requires consistent effort to rebuild trust with ISPs.

Key opinions

• Beyond authentication: Many marketers acknowledge that passing SPF, DKIM, and DMARC is fundamental but insufficient alone to guarantee inbox delivery. Other factors weigh heavily.
• Reputation is paramount: A damaged sender reputation, often stemming from past sending practices or even malicious activity like API abuse, is frequently cited as the primary reason for poor inbox placement. Even marketing emails can go to Gmail spam due to this.
• Low volume challenges: For B2B senders or those with naturally low email volumes, building and maintaining a strong reputation is exceptionally difficult. Mailbox providers have less data to evaluate trust.
• Hidden technicalities: Sometimes, subtle DNS issues, not directly related to SPF, DKIM, or DMARC, can still impact delivery. This might include issues with PTR records or CERT lookups.
• Content and user feedback: Regardless of technical compliance, email content that is perceived as spammy or generates complaints will consistently trigger filters. User interaction is key; low engagement hurts deliverability.

Key considerations

• Proactive reputation management: Marketers must closely monitor their domain reputation using tools like Google Postmaster Tools. This provides a direct feedback loop from major ISPs.
• Investigate past incidents: Any prior issues, such as API abuse leading to a flood of spam registrations, need to be identified and thoroughly addressed. The long-term impact on reputation can be significant.
• Strategic sending volume: For low-volume senders, maintaining consistency and ensuring high engagement from a small, highly qualified list is paramount to building trust. You can also refer to our article on new domains landing in spam.
• Refine content and list hygiene: Continuously optimize email content for relevance and clarity. Regularly clean your email lists to remove inactive or problematic addresses to improve engagement metrics.
• Seek expert consultation: If persistent problems remain despite self-troubleshooting, engaging an email deliverability consultant or leveraging ISP support channels (like Google Workspace support for Gmail issues) is advisable.

Key opinions

• Domain reputation matters more: Experts universally agree that poor domain or IP reputation is the leading cause for emails landing in spam, even when authentication passes. This reputation is built over time based on sending behavior.
• Volume sensitivity: Low send volume can make it difficult to establish and improve sender reputation, as ISPs have less data to assess trustworthiness. This is particularly challenging for new domains or those with inconsistent sending patterns.
• Content quality and engagement: Beyond authentication, ISPs heavily scrutinize email content for spam indicators and rely on recipient engagement signals. High complaint rates, low open rates, and bounces can severely degrade deliverability.
• Hidden blocklistings: Even if public blocklist checks show clear, private internal blocklists maintained by large ISPs or specific recipient organizations can still block or filter emails. Our guide on what happens when your domain is blocklisted offers more details.
• Persistence of past issues: One-off incidents of sending spam, even if quickly resolved, can have a prolonged negative impact on reputation with major mailbox providers like Google. This requires a dedicated recovery effort.

Key considerations

• Holistic deliverability auditing: Beyond authentication, conduct comprehensive audits covering IP/domain reputation, email content, list quality, and engagement metrics. Use tools like Google Postmaster Tools for invaluable insights into your domain reputation in Google Postmaster Tools.
• Proactive relationship with ISPs: Establish direct lines of communication where possible, especially with major ISPs. Utilizing their feedback loops and postmaster pages is crucial for understanding specific issues.
• Long-term reputation building: If reputation has been damaged, commit to a long-term strategy involving sending only highly engaged content, cleaning lists, and consistent volume. Recovery can take months.
• Spam trap avoidance: Regular list hygiene is essential to avoid hitting spam traps, which are a major indicator of poor list quality and can severely damage sender reputation, regardless of authentication.
• Consult external expertise: For deeply entrenched deliverability issues, engaging an experienced email deliverability consultant can provide tailored strategies and insights that automated tools might miss. Consider strategies to avoid email going to spam.

Key findings

• Authentication is a baseline: Documentation confirms that SPF, DKIM, and DMARC are necessary to establish sender authenticity, but they do not account for overall sender quality or recipient desire for the email.
• Sender reputation is paramount: ISPs weigh sender reputation heavily, which is influenced by factors such as complaint rates, bounce rates, spam trap hits, and engagement metrics. A poor reputation leads to spam filtering regardless of authentication.
• Content analysis: Email content is rigorously analyzed for spammy characteristics, including suspicious keywords, malicious links, and poor formatting. Even legitimate senders can trigger filters with poorly constructed messages.
• Engagement signals: Positive user engagement (opens, clicks, replies) and low negative engagement (spam complaints, deletions without opening) are crucial signals that documentation emphasizes for good inbox placement.
• DNS health beyond authentication: Beyond SPF, DKIM, and DMARC, documentation sometimes alludes to the importance of other DNS records, like PTR records, and general DNS health for overall mail server credibility.

Key considerations

• Adhere to best practices: Documentation consistently advises adherence to email sending best practices, including maintaining clean lists, managing subscriber expectations, and providing clear unsubscribe options.
• Utilize Postmaster Tools: Major email providers like Google and Outlook offer Postmaster Tools that provide vital deliverability insights, including reputation metrics, spam rates, and DMARC reports. These are essential for diagnosis.
• Continuous monitoring: Documentation implies that deliverability is not a set-it-and-forget-it task. Continuous monitoring of metrics and prompt response to any dips in performance are critical.
• Content compliance: Even with perfect authentication, content must comply with anti-spam policies of target ISPs. This includes avoiding deceptive practices and adhering to legal requirements like CAN-SPAM or GDPR.
• Understand ISP specific nuances: Documentation from different ISPs might highlight specific requirements or filters unique to their systems, necessitating a nuanced approach to deliverability across various providers.