Summary
Even with a good domain reputation, emails can still be marked as spam due to a multitude of factors. These include technical aspects like improper email authentication (SPF, DKIM, DMARC), being listed on blocklists (even unintentionally), using a shared IP address with a poor reputation, and not warming up a new IP address properly. Content issues, such as spam trigger words or poorly formatted HTML, can also trigger filters. Engagement metrics like low open rates and click-through rates, combined with high spam complaint rates, significantly impact deliverability, as ISPs prioritize user experience. Finally, permission issues, where users receive emails without consent, and poor list hygiene contribute to spam placement. Low bounce and complaint rates can be misleading if bounce handling is in place or the target audience doesn't actively complain.
Key findings
- Multifactorial Filtering: Spam filtering is based on a combination of technical, content, engagement, and reputation factors.
- User Feedback Reigns Supreme: User complaints are a primary driver of spam filtering, often overriding technical setup.
- Authentication is Non-Negotiable: Proper SPF, DKIM, and DMARC configuration is essential for deliverability.
- Engagement Impacts Deliverability: Low engagement (opens, clicks) and high spam complaints negatively impact deliverability.
- Permission is Paramount: Sending emails to users who have not explicitly opted in leads to spam filtering.
- Blocklists Matter: Being listed on blocklists can override positive domain reputation.
- Content is Critical: Spammy content and poor HTML increase the likelihood of spam filtering.
- IP Reputation Key: Shared IP or new IP impacts are key.
Key considerations
- Implement Authentication: Ensure SPF, DKIM, and DMARC are properly configured and validated.
- Monitor Reputation: Regularly check for blocklist listings and maintain a clean IP reputation.
- Optimize Content: Avoid spam trigger words, use clean HTML, and ensure a clear unsubscribe process.
- Improve Engagement: Create engaging content, segment audiences, and personalize emails to increase open and click-through rates.
- Manage Complaints: Monitor spam complaint rates and address any underlying issues that may be causing them.
- Gain Explicit Permission: Only send emails to users who have explicitly opted in and provide a clear unsubscribe option.
- Practice List Hygiene: Regularly clean email lists to remove inactive or invalid addresses.
- IP Warm Up Process: Warm up new IPs to ensure email deliverability.
- Review Bulk Guidelines: Ensure bulk senders guidelines are adhered to.
What email marketers say
7 marketer opinions
Even with a good domain reputation, emails can still be marked as spam due to various factors. These include low engagement (open and click-through rates), high spam complaint rates, problematic email content (spam trigger words or poorly formatted HTML), poor list hygiene (sending to inactive/invalid addresses), using a shared IP address with spammers, and improper email authentication (SPF, DKIM, DMARC). Furthermore, a new IP address needs to be warmed up gradually to build a sending reputation.
Key opinions
- Engagement Matters: Low engagement rates (opens, clicks) can lead to spam filtering despite a good domain reputation.
- Complaints Override Reputation: A high spam complaint rate can override a good domain reputation.
- Content Matters: Spammy content and poor HTML can trigger filters.
- List Hygiene is Crucial: Poor list hygiene negatively impacts deliverability.
- Shared IPs Can Hurt: Using a shared IP can cause deliverability issues if other users on the IP send spam.
- Authentication is Key: Proper email authentication (SPF, DKIM, DMARC) is necessary to avoid spam filters.
- IP Warm-up Is Necessary: Gradually increase email volume when starting with a new IP.
Key considerations
- Improve Engagement: Focus on creating engaging content that encourages opens and clicks.
- Reduce Complaints: Ensure recipients have explicitly opted in and make it easy to unsubscribe.
- Optimize Content: Avoid spam trigger words and use clean, well-formatted HTML in email content.
- Clean Your Lists: Regularly remove inactive and invalid email addresses from your lists.
- Consider Dedicated IP: If deliverability issues persist, consider using a dedicated IP address.
- Implement Authentication: Ensure SPF, DKIM, and DMARC records are properly configured.
- Warm Up IPs: Warm up new IPs slowly.
Marketer view
Email marketer from HubSpot says gradually increasing the volume of emails sent from a new IP address to build a sending reputation is a vital step to ensure deliverability to the inbox instead of the spam folder.
24 Mar 2023 - HubSpot
Marketer view
Email marketer from Email Marketing Forum explains that a high complaint rate (even a small percentage) can override a good domain reputation. ISPs prioritize user experience and will filter emails reported as spam.
29 Mar 2024 - Email Marketing Forum
What the experts say
5 expert opinions
Even with a good domain reputation, emails can still be marked as spam. While specific tools like Razor2 might not be the direct cause, the underlying issues leading to its listing can be factors considered by major email providers. Spam filtering ultimately depends on user preferences and complaint rates. ISPs prioritize user experience, so even a technically sound setup can be overridden by a high volume of spam reports from recipients. Permission issues, where users receive emails without explicit consent, can also lead to spam placement. Finally, low bounce and complaint rates may be misleading if you're handling bounces or sending to domains where complaints are less common, or if your mail is going to the bulk/spam folder automatically.
Key opinions
- Underlying Issues Matter: Problems that cause Razor2 listings can also impact deliverability with other providers.
- Complaints Drive Filtering: User complaints significantly impact filtering decisions, overriding technical setup.
- Permission is Key: Sending emails to users without consent is a major cause of spam filtering.
- ISPs Filter Based on User Preference: ISPs filter emails based on user spam reports, which is independent of overall sender reputation
- Misleading Metrics: Low bounce and complaint rates do not always tell the full story.
Key considerations
- Address Root Causes: Investigate and resolve issues that lead to Razor2 listings or similar problems.
- Monitor Complaints: Actively monitor and address spam complaints, even if the rate seems low.
- Verify Permissions: Ensure all recipients have explicitly opted in to receive emails.
- Understand ISP-Specific Filtering: Consider testing email placement with different ISPs to see how filtering differs.
- Investigate Bulk/Spam Folder Placement: Probe addresses to see if mail is being delivered, but going to the spam or bulk folder.
Expert view
Expert from Email Geeks explains that low bounce rates could be due to bounce handling and lack of complaints could be due to sending primarily to Gmail/business domains or mail going to the bulk folder. If seeing spam placement for probe addresses, there is likely a problem with permission, and addresses are receiving mail without signing up.
5 Oct 2024 - Email Geeks
Expert view
Expert from Word to the Wise explains that complaints drive a lot of filtering decisions. Even if your technical setup (authentication, IP reputation) is perfect, a high complaint rate can still cause your emails to go to the spam folder.
19 Feb 2024 - Word to the Wise
What the documentation says
4 technical articles
Even with a good domain reputation, emails can still be marked as spam. Gmail's filtering considers sender authentication, user reports, and email content, emphasizing that reputation is just one piece of the puzzle. Outlook's SmartScreen filter learns from user feedback and heuristics, meaning even a well-reputed sender can be flagged if their individual emails trigger the filter or are reported as spam. Spamhaus blocklists can also override a good reputation if an IP address or domain is associated with spam activity, even unintentionally. Properly setting up a DMARC record in DNS is important so receivers know how to handle failed authentication attempts.
Key findings
- Holistic Filtering: Gmail uses multiple factors beyond domain reputation for spam filtering.
- User Feedback Matters: Outlook's SmartScreen filter learns from user feedback, influencing spam classification.
- Blocklists Override: Spamhaus blocklisting can override a positive domain reputation.
- DMARC is Important: DMARC enables senders to specify how receivers should handle unauthenticated messages.
Key considerations
- Review Authentication: Ensure SPF, DKIM, and DMARC are properly configured to authenticate your emails.
- Monitor User Reports: Pay attention to user feedback and spam reports to identify potential issues.
- Maintain IP Integrity: Ensure your IP address isn't associated with spam activity or listed on blocklists.
- Review Content: Carefully review email content for spam triggers and ensure adherence to best practices
- Bulk Sender Guidelines: Ensure all bulk sender guidelines are adhered to.
Technical article
Documentation from Google Workspace Admin Help explains that Gmail filters spam based on many factors, including sender authentication (SPF, DKIM, DMARC), user reports, and content. Good domain reputation is important, but not the only factor. They recommend reviewing their bulk sender guidelines.
10 Dec 2021 - Google Workspace Admin Help
Technical article
Documentation from RFC answers details how the DMARC record in DNS allows senders to indicate that their messages are protected by SPF and/or DKIM, and gives instructions to receivers if neither of those authentication methods pass.
18 Jan 2023 - RFC 6376
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