Summary
Even when emails pass SPF, DKIM, and DMARC authentication, they can still land in spam due to a complex interplay of factors. A sender's IP and domain reputation are paramount, influencing deliverability to major providers like Gmail, Outlook.com, and Hotmail. User engagement, including open and click rates, plays a critical role, as low engagement signals unwanted emails. Email content is scrutinized by spam filters for suspicious keywords, poor formatting, and broken HTML. Smaller, industry-specific blocklists can affect deliverability, and shared IP addresses may carry a negative reputation. New IP addresses need gradual warm-up to build trust. DMARC policy, high bounce rates, sending frequency, personalization, and email list hygiene are all significant factors. B2B senders face particular challenges in building reputation due to lower send volumes. Consistent monitoring and proactive adjustments are essential.
Key findings
- Reputation is King: Sender IP and domain reputation are overriding factors for deliverability, even with proper authentication.
- Engagement Matters: Low user engagement (opens, clicks) negatively impacts deliverability.
- Content Still Counts: Spam filters analyze content for suspicious keywords, poor formatting, and broken HTML.
- Blacklists Can Still Impact: Smaller, industry-specific blocklists can affect deliverability even if not on major lists.
- Shared IPs are Risky: Shared IP addresses can negatively impact deliverability, especially if 'dirty'.
- Warm-up is Essential: New IP addresses require gradual warm-up to build reputation.
- B2B Has Unique Challenges: B2B senders face challenges in building reputation due to lower volume.
- Complaint Rates Matter: High spam complaint rates significantly hurt deliverability.
- Bounce Rate Impacts: High bounce rates signal poor list hygiene and can degrade reputation.
- Sending Frequency: Sending frequency matters, sending too much or too little can degrade reputation.
- DMARC Policy: DMARC policy impacts what happens to messages failing authentication.
- List Hygiene: Poor list hygiene will reduce deliverability.
Key considerations
- Monitor Reputation: Regularly monitor sender reputation using tools like Google Postmaster Tools and Microsoft SNDS.
- Optimize Content: Refine email content to avoid spam triggers, focusing on clear language and proper formatting.
- Increase Engagement: Segment email lists and send targeted, personalized content to improve engagement rates.
- Check Blocklists: Periodically check sending IP and domain against various blocklists.
- Consider Dedicated IP: For larger senders, consider using a dedicated IP address.
- Warm-up New IPs: Properly warm-up new IP addresses by gradually increasing sending volume.
- Use Testing Tools: Use deliverability testing tools to identify specific issues.
- Clean Your List: Regularly clean email lists to remove unengaged and invalid addresses.
- Avoid Spammy Content: Review all email content for spam triggers before sending.
- Be Personal: Ensure emails are personalized.
- Control Sending Frequency: Find the right sending frequency.
What email marketers say
10 marketer opinions
Even when emails pass SPF, DKIM, and DMARC authentication, they can still land in spam due to various factors beyond technical setup. These factors include sender reputation, email content, user engagement, and infrastructure issues. Maintaining a positive sender reputation, creating engaging and well-designed content, practicing good list hygiene, and properly configuring sending infrastructure are crucial for inbox placement.
Key opinions
- Sender Reputation: Poor sender reputation, based on past sending practices and user engagement, overrides authentication and leads to spam classification.
- Content Triggers: Spam filters analyze email content for suspicious keywords, excessive links, poor formatting, and broken HTML, regardless of authentication.
- Engagement Metrics: Low engagement rates (opens, clicks) signal to mailbox providers that emails are unwanted, leading to spam placement.
- Blocklist Status: Sending IP or domain may be listed on a blocklist, even if not a major one, affecting deliverability.
- Shared IP Issues: Using a shared IP address, especially a 'dirty' one, negatively impacts deliverability.
- New IP Warm-up: Failing to properly warm up a new IP address results in spam placement.
- Personalization Matters: Lack of personalization decreases user engagement, leading to higher chances of emails landing in the spam folder.
- Email Frequency: Sending emails with high frequency may annoy recipients and can lead to a high amount of spam reports, whereas a low frequency may cause users to forget who you are and thus disengage.
Key considerations
- Monitor Reputation: Regularly monitor sender reputation using tools like Google Postmaster Tools and Microsoft SNDS.
- Optimize Content: Refine email content to avoid spam triggers, focusing on clear language, relevant links, and proper formatting.
- Improve Engagement: Segment email lists and send targeted, personalized content to improve engagement rates.
- Check Blocklists: Periodically check sending IP and domain against various blocklists, including smaller, industry-specific ones.
- Consider Dedicated IP: For larger senders, consider using a dedicated IP address to control reputation.
- Warm-up IP: Properly warm-up new IP addresses by gradually increasing sending volume.
- Use Deliverability Testing: Use deliverability testing tools to identify specific issues causing spam placement.
- Maintain list hygiene: Consistently clean and prune your mailing lists to ensure higher engagement rates and avoid spam reports.
Marketer view
Email marketer from GlockApps shares that using a deliverability testing tool can identify specific issues causing spam placement, such as content issues or problems with specific mailbox providers, despite passing authentication.
17 Jun 2023 - GlockApps
Marketer view
Email marketer from Reddit explains that low engagement rates (opens, clicks) signal to mailbox providers that your emails are unwanted, leading to spam placement despite proper authentication. They suggest focusing on list hygiene and relevant content.
6 Jun 2023 - Reddit
What the experts say
6 expert opinions
Even with proper SPF, DKIM, and DMARC authentication, emails can still land in spam. This is primarily due to factors such as low domain reputation, content triggering spam filters, sending to unengaged addresses, and high complaint rates. B2B companies with lower send volumes face more challenges in building a strong reputation. Prioritizing list hygiene and avoiding spam-like content are crucial for improving deliverability.
Key opinions
- Low Domain Reputation: Low domain reputation, especially with low send volume, can cause emails to land in spam even with proper authentication.
- B2B Reputation Challenges: Building reputation is harder for B2B companies due to lower send volumes and fewer touchpoints compared to B2C.
- Content Filters: Content filters analyze emails for spam-like characteristics, such as certain keywords and excessive HTML, regardless of authentication.
- Unengaged Addresses: Sending to old or unengaged email addresses negatively impacts deliverability.
- High Complaint Rates: High complaint rates (spam reports) are a major factor in spam filtering, even with authentication.
Key considerations
- Build Domain Reputation: Focus on strategies to build a positive domain reputation, such as consistent sending practices and engaging content.
- Improve B2B Engagement: Explore strategies to increase touchpoints and engagement in B2B contexts, despite lower send volumes.
- Optimize Email Content: Refine email content to avoid triggers that might flag emails as spam.
- Maintain List Hygiene: Regularly clean email lists to remove unengaged addresses.
- Monitor Complaint Rates: Actively monitor complaint rates and investigate the causes of negative feedback.
Expert view
Expert from Email Geeks explains it is much harder than B2C where you have (in theory) higher volumes and more touch points with which to adjust the rudder to steer your reputation.
9 Oct 2023 - Email Geeks
Expert view
Expert from Spamresource shares that even with perfect technical setup (SPF, DKIM, DMARC), poor sender reputation can override authentication and cause emails to land in spam. Reputation is built over time based on user engagement and sending practices.
30 Jan 2022 - Spamresource
What the documentation says
4 technical articles
Even with passing SPF, DKIM, and DMARC, email deliverability can be negatively impacted. Google Postmaster Tools highlights the importance of IP and domain reputation for Gmail delivery. Microsoft SNDS emphasizes the impact of user feedback, specifically spam reports, on Outlook.com and Hotmail deliverability. RFC documentation explains the role of DMARC policy in handling authentication failures and advises gradual policy implementation. SparkPost points out that high bounce rates harm sender reputation and increase spam filtering.
Key findings
- Sender Reputation Matters: IP and domain reputation significantly influence deliverability, overriding authentication in some cases (Google).
- User Feedback is Crucial: Negative user feedback (spam reports) severely impacts deliverability to Microsoft email services (Microsoft).
- DMARC Policy Implementation: DMARC policy dictates how unauthenticated emails are handled, requiring careful and gradual implementation (RFC).
- High Bounce Rates Impact: High bounce rates damage sender reputation, leading to increased spam filtering (SparkPost).
Key considerations
- Monitor Sender Reputation: Use Google Postmaster Tools to monitor IP and domain reputation for Gmail delivery.
- Reduce Spam Complaints: Minimize spam complaints to improve deliverability to Microsoft email services.
- Implement DMARC Gradually: Implement DMARC policy carefully, starting with a monitoring policy before moving to quarantine or reject.
- Maintain Clean Email List: Regularly clean email lists to reduce bounce rates and protect sender reputation.
Technical article
Documentation from RFC explains that DMARC policy settings (p=quarantine or p=reject) impacts what happens to messages failing authentication. The DMARC policy needs to be set to gradually increase to ensure all legitimate emails are authenticating correctly.
28 Jun 2024 - RFC
Technical article
Documentation from SparkPost shares that high bounce rates can negatively impact a sender’s reputation, leading to increased spam filtering. It’s important to regularly clean email lists and remove invalid addresses.
7 Nov 2024 - SparkPost
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