Why are my emails going to spam after IP warming despite good domain reputation?

Summary

Despite a good domain reputation, emails may still go to spam after IP warming due to a multitude of factors. Incorrect or incomplete email authentication (SPF, DKIM, DMARC) for the new IP is a major issue. Other factors include technical configuration problems (rDNS, HELO), content triggering spam filters, unexpected reputation changes post-warming, and the actions of other users on shared IPs. Furthermore, low engagement metrics, sending to inactive addresses, inconsistent volume, and not monitoring feedback loops also contribute. Properly warming the IP with gradual increases, practicing list hygiene, ensuring relevant content, and monitoring sender reputation are critical for inbox placement.

Key findings

  • Authentication: Incorrect or incomplete SPF, DKIM, and DMARC configurations for the new IP address are a primary cause of deliverability issues.
  • Technical Configuration: Incorrect rDNS, HELO settings, IP source, and SWIP status can negatively impact deliverability.
  • Content: Email content may contain spam triggers, leading to filtering.
  • Reputation: IP reputation can change unexpectedly post-warming, necessitating constant monitoring.
  • Shared IP: On shared IPs, the actions of other users affect deliverability regardless of your domain reputation.
  • Engagement: Low open rates, click-through rates, and high spam complaint rates negatively impact inbox placement.
  • List Quality: Sending to inactive or unengaged email addresses damages sender reputation.
  • Volume: Fluctuations in email sending volume can cause deliverability problems.

Key considerations

  • Authentication Check: Meticulously verify SPF, DKIM, and DMARC records for the new IP address.
  • Technical Audit: Perform a thorough audit of rDNS, HELO settings, IP source, and SWIP status.
  • Content Review: Regularly review email content for potential spam-triggering keywords.
  • Reputation Monitoring: Continuously monitor IP reputation and adjust sending practices accordingly.
  • Dedicated IP Consideration: If using a shared IP, consider moving to a dedicated IP if problems persist.
  • Warming Process: Gradually warm up the IP address with small batches to engaged subscribers.
  • List Hygiene: Regularly clean email lists to remove inactive subscribers and invalid addresses.
  • Feedback Loops: Enroll in feedback loops with major ISPs to identify and address spam complaints.
  • Consistent Volume: Maintain a consistent email sending volume.
  • Segmentation: Segment your list and send relevant content
  • Testing: Use seed list testing to monitor deliverability issues across different ISPs.

What email marketers say
11Marketer opinions

Emails may land in spam after IP warming despite a good domain reputation due to a combination of factors. These include incorrect or incomplete email authentication (SPF, DKIM, DMARC) setup for the new IP, sending to inactive or unengaged email addresses, inconsistent sending volumes, content triggering spam filters, and not adequately monitoring or reacting to deliverability metrics. Gradual IP warming, proper list hygiene, relevant content, engagement with feedback loops, consistent volume, and thorough testing are crucial for maintaining good inbox placement.

Key opinions

  • Authentication: Incomplete or incorrect SPF, DKIM, and DMARC configurations post-IP warming can lead to deliverability issues.
  • Spam Triggers: Spammy words and phrases, as well as HTML rendering issues, can trigger spam filters.
  • Engagement Metrics: Low open rates, click-through rates, and high spam complaint rates negatively impact inbox placement.
  • Warming Process: Incorrectly warming IPs with high volumes or sending to unengaged segments can cause delivery problems.
  • List Quality: Sending to inactive email addresses, bounces, or spam traps damages sender reputation.
  • Volume: Sending inconsistent volume can cause delivery issues, even with domain reputation.

Key considerations

  • Authentication Check: Verify and correct SPF, DKIM, and DMARC records for the new IP address.
  • Content Review: Review email content for spam triggers and ensure proper HTML rendering across different email clients.
  • Engagement Monitoring: Monitor open rates, click-through rates, and spam complaints, and adjust sending practices accordingly.
  • Gradual Warming: Warm up the IP address gradually, starting with small batches of engaged subscribers.
  • List Hygiene: Clean email lists regularly to remove inactive subscribers, invalid email addresses, and spam traps.
  • Feedback Loops: Enroll in feedback loops with major ISPs to identify and address spam complaints quickly.
  • Consistent Volume: Ensure a consistent volume of emails daily.
  • Segmentation: Segment your lists and send targeted content
  • Testing: Use seed list testing to monitor deliverability issues
Marketer view

Email marketer from Stack Overflow recommends using email testing tools to preview emails across different email clients and devices, ensuring optimal rendering and reducing the likelihood of being marked as spam.

March 2023 - Stack Overflow
Marketer view

Email marketer from Campaign Monitor explains that segmenting your email list and sending targeted content to specific groups can improve engagement metrics and reduce the likelihood of emails being marked as spam.

September 2023 - Campaign Monitor
Marketer view

Email marketer from Mailjet emphasizes the importance of gradually increasing sending volume during IP warming, starting with small batches to engaged subscribers. They also recommend monitoring deliverability metrics closely and adjusting sending practices as needed.

July 2021 - Mailjet
Marketer view

Email marketer from Neil Patel's Blog explains that common spam triggers include using spammy words, having a poor sender reputation, not authenticating emails (SPF, DKIM, DMARC), and sending to inactive email addresses.

June 2024 - Neil Patel's Blog
Marketer view

Email marketer from Sendinblue shares that several factors influence inbox placement, including sender reputation, email authentication, engagement metrics (open rates, click-through rates), spam complaints, and the content of the email itself.

April 2022 - Sendinblue
Marketer view

Email marketer from HubSpot advises that enrolling in feedback loops with major ISPs helps identify and address spam complaints quickly, improving sender reputation and deliverability.

January 2023 - HubSpot
Marketer view

Email marketer from Email on Acid emphasizes that sending relevant and engaging content to subscribers increases open rates and click-through rates, signaling to ISPs that the email is wanted and reducing the chances of it being marked as spam.

November 2023 - Email on Acid
Marketer view

Email marketer from Litmus recommends that maintaining clean email lists is crucial. Regularly remove inactive subscribers and invalid email addresses to improve engagement rates and sender reputation.

July 2021 - Litmus
Marketer view

Marketer from Email Geeks explains that building a sending reputation with a dedicated IP takes time and requires a warmup plan. The low volume of test messages might not be sufficient signals for filters. Also, there might be a problem with email authentication (SPF, DKIM, or DMARC).

March 2021 - Email Geeks
Marketer view

Email marketer from GlockApps recommends using seed list testing to monitor inbox placement across different ISPs. This helps identify deliverability issues early and make necessary adjustments.

January 2025 - GlockApps
Marketer view

Email marketer from Reddit suggests ensuring you are sending a consistent volume of emails daily to maintain your IP reputation. Fluctuations can negatively impact deliverability, even with good domain reputation.

November 2021 - Reddit

What the experts say
5Expert opinions

Emails may still land in spam post-IP warming, even with a strong domain reputation, due to several technical and environmental factors. These include incorrect rDNS or HELO settings, improperly configured or verified SPF, DKIM, and DMARC records (especially crucial for new IPs), content that triggers spam filters, unexpected reputation changes post-warming requiring vigilant monitoring, or issues related to shared IP environments where other users' behavior affects deliverability. Consistent volume and persistence are also important if all technical aspects are correctly configured.

Key opinions

  • Technical Configuration: rDNS, HELO settings, IP source, and SWIP status are critical technical elements to verify during IP warming.
  • Authentication: Meticulous verification of SPF, DKIM, and DMARC configurations is essential, especially for new IPs.
  • Content Filtering: Email content may contain triggering keywords that activate spam filters.
  • Reputation Changes: IP reputation can change unexpectedly post-warming, requiring ongoing monitoring.
  • Shared IP Impact: In shared IP environments, the actions of other users can negatively affect deliverability.
  • Volume and Persistence: Maintaining consistent sending volume and persistent effort are crucial if all other factors are correctly configured.

Key considerations

  • Technical Audit: Conduct a thorough audit of rDNS, HELO settings, IP source, and SWIP status.
  • Authentication Verification: Verify and meticulously configure SPF, DKIM, and DMARC records for the new IP.
  • Content Review: Review email content for potential spam-triggering keywords.
  • Reputation Monitoring: Continuously monitor IP reputation post-warming for any unexpected changes.
  • Dedicated IP: Consider switching to a dedicated IP if deliverability issues persist in a shared IP environment.
  • Consistent Volume: Maintain a consistent email sending volume to build and maintain a positive sender reputation.
Expert view

Expert from Spam Resource explains that even with a good domain reputation, issues during or after IP warming can stem from poor email authentication configurations (SPF, DKIM, DMARC). He emphasizes the need to meticulously verify these settings and ensure they are correctly implemented for the new IP address.

February 2022 - Spam Resource
Expert view

Expert from Email Geeks suggests checking rDNS, HELO settings, IP source and SWIP status, neighbors, upstream ASN, and spam destination when troubleshooting IP warming issues.

March 2021 - Email Geeks
Expert view

Expert from Email Geeks shares that if everything is correctly configured (wanted mail, proper reputation building, SPF/DKIM/DMARC), persistence is key. If problems persist, the issue might be related to volume, either too much or not enough.

August 2023 - Email Geeks
Expert view

Expert from Word to the Wise explains that problems after IP warming can relate to content filtering issues or unexpected reputation changes. She suggests reviewing email content for potentially triggering keywords and monitoring IP reputation post-warming, as providers might adjust filtering rules dynamically.

May 2023 - Word to the Wise
Expert view

Expert from Spam Resource shares that if you’re warming a shared IP, the actions of other users on that IP can impact your deliverability, regardless of your domain reputation. He suggests closely monitoring deliverability and considering a dedicated IP if problems persist.

September 2024 - Spam Resource

What the documentation says
5Technical articles

Emails may land in spam after IP warming, despite a good domain reputation, because of technical and policy requirements outlined by major email providers and industry standards. These include proper email authentication using SPF, DKIM, and DMARC; maintaining low spam complaint rates (below 0.1% as per Google's guidelines); avoiding sending unsolicited or unwanted email; making unsubscribing easy; and monitoring sender reputation with ISPs like Microsoft Outlook. Effective sender reputation management is vital for consistent inbox placement, as email providers use various signals including content, user feedback, and engagement metrics to filter emails.

Key findings

  • Authentication: Proper email authentication (SPF, DKIM, DMARC) is a fundamental requirement for deliverability.
  • Spam Rate: Maintaining a low spam complaint rate (ideally below 0.1%) is crucial for inbox placement.
  • Unsolicited Mail: Avoid sending unsolicited or unwanted email to prevent being marked as spam.
  • Unsubscribe Process: Making it easy for recipients to unsubscribe is essential for compliance and maintaining a good sender reputation.
  • Sender Reputation: Sender reputation is a critical factor influencing inbox placement, monitored by ISPs using various signals.

Key considerations

  • Implement Authentication: Implement and verify SPF, DKIM, and DMARC records for all sending domains.
  • Monitor Spam Complaints: Monitor and address spam complaints promptly to keep the rate below the recommended threshold.
  • Obtain Consent: Ensure recipients have explicitly consented to receive emails.
  • Simplify Unsubscribing: Provide a clear and easy unsubscribe process in every email.
  • Reputation Monitoring: Regularly monitor sender reputation with major ISPs like Microsoft and Google.
Technical article

Documentation from Validity (formerly ReturnPath) notes that sender reputation is a critical factor in email deliverability. Maintaining a positive reputation with ISPs is essential for inbox placement.

February 2023 - Validity
Technical article

Documentation from Google Bulk Sender Guidelines specifies that senders must authenticate their email using SPF, DKIM, and DMARC. They also must keep spam rates below 0.1% and avoid sending unwanted mail. They must also make it easy to unsubscribe.

August 2021 - Google Bulk Sender Guidelines
Technical article

Documentation from Microsoft explains that Outlook.com uses a variety of signals to filter email, including sender reputation, content filtering, and user feedback. Senders should monitor their reputation and address any issues promptly.

March 2025 - Microsoft
Technical article

Documentation from RFC 4871 describes how to generate DKIM signatures by using cryptographic keys and adding a DKIM-signature header to outbound emails. It provides detailed steps on generating the keys and using them.

February 2024 - RFC 4871
Technical article

Documentation from RFC 4408 details the correct syntax for SPF records, explaining the use of mechanisms (e.g., 'a', 'mx', 'ip4', 'include') and qualifiers (+, -, ~, ?) to specify authorized sending sources.

July 2021 - RFC 4408