Summary
Troubleshooting Yahoo TSS04 delivery errors in shared IP pools involves a comprehensive approach encompassing immediate actions and proactive strategies. Initially, waiting 24 hours is advised as the error can be temporary. Subsequently, a thorough investigation into recent sending practices is crucial, focusing on identifying potentially problematic senders exhibiting increased volumes, new subscriber uploads, or altered sending behaviors. Key actions include pausing sends from these senders and drastically reducing overall sending volume, targeting only engaged subscribers. Maintaining a pristine list through active removal of inactive recipients, managing unsubscribes, and addressing feedback loops is paramount. Proactive measures involve implementing sending rate throttling to prevent overwhelming Yahoo's servers, continuous monitoring of sender reputation metrics (bounce rates, complaint rates, spam trap hits), and ensuring proper email authentication (SPF, DKIM, DMARC). When issues persist, engaging with Yahoo support is recommended to gain further insights.
Key findings
- Pause & Reduce Volume: Immediately pause sends from problematic senders and reduce volume to engaged subscribers to avoid exacerbating the problem.
- Identify Problematic Senders: Identify senders with increased volumes, new subscriber uploads, or changed sending behavior within the shared IP pool. Look for customers who had an increase of sends to Yahoo around that day and the day prior, and who were first to get the TSS04 notices.
- Monitor Engagement & Hygiene: Monitor engagement metrics (opens, clicks), feedback loops, unsubscribes, and maintain a clean, permission-based list. Remove disengaged or unengaged recipients.
- Implement Throttling: Implement sending rate throttling to prevent overwhelming Yahoo's servers. Gradual ramp-up of sending volume after detecting issues and monitoring sending speed are also recommended.
- Engage with Yahoo Support: Engage with Yahoo support and provide detailed information about sending practices if the issue persists despite remediation efforts. Keep asking for more information.
- Sender Reputation is Key: Maintain a strong sender reputation. This includes ensuring proper authentication (SPF, DKIM, DMARC), keeping complaint rates low, and actively managing your subscriber list to remove inactive or disengaged recipients. Consistent monitoring of sender reputation metrics is essential.
- Check IP Reputation: Check your IP's reputation using online tools such as Talos Intelligence. If there are any reputation issues, then the solution is to make sure that the email list is clean, that there are not too many bounces, that users are not marking emails as spam, and that there is a low unsubscribe rate.
- Hard Bounce Suppression: Hard bounces should be suppressed immediately.
- Investigate sending practices: TSS04 errors are often vague, necessitating a review of recent sending practices across the shared IP pool.
Key considerations
- Shared Pool Challenges: Managing shared IP pools requires diligent oversight to ensure all senders adhere to best practices.
- Root Cause Analysis: Thoroughly investigate sending patterns and data to determine the underlying cause of TSS04 errors.
- Proactive Measures: Implement proactive measures like list segmentation and engagement monitoring to prevent future issues.
- Authentication is Crucial: Ensure proper email authentication (SPF, DKIM, DMARC) is configured correctly.
- Thoroughness Required: Addressing TSS04 errors requires a thorough investigation into various factors.
- Suppression: Hard bounces should be immediately suppressed from your email lists.
- Consistant Sending: Send emails with a consistent sending frequency, as well as ensure that you maintain a low complaint rate.
What email marketers say
11 marketer opinions
Troubleshooting Yahoo TSS04 delivery errors for shared IP pools involves several key strategies. Primarily, it's crucial to identify and address the root cause, often related to sending practices of clients within the shared pool. This includes monitoring sending volumes, engagement metrics, and list hygiene. Immediate actions involve pausing sends from problematic senders and reducing overall volume to highly engaged users. Proactive measures include implementing throttling, segmenting lists based on engagement, monitoring IP reputation, and ensuring proper email authentication. Engaging with Yahoo support, while not always immediately helpful, can provide insights if issues persist despite best practices.
Key opinions
- Pause & Reduce Volume: Immediately pause sending and reduce volume to engaged subscribers to avoid exacerbating the problem.
- Identify Problematic Senders: Identify senders with increased volumes, new subscriber uploads, or changed sending behavior within the shared IP pool.
- Monitor Engagement & Hygiene: Monitor engagement metrics (opens, clicks), feedback loops, unsubscribes, and maintain a clean, permission-based list.
- Implement Throttling: Implement sending rate throttling to prevent overwhelming Yahoo's servers.
- Engage with Yahoo Support: Engage with Yahoo support and provide detailed information about sending practices if the issue persists despite remediation efforts.
- Monitor IP Reputation: Regularly check IP reputation to be alerted to any reputation issues and take immediate action.
Key considerations
- Shared Pool Challenges: Managing shared IP pools requires diligent oversight to ensure all senders adhere to best practices.
- Root Cause Analysis: Thoroughly investigate sending patterns and data to determine the underlying cause of TSS04 errors.
- Proactive Measures: Implement proactive measures like list segmentation and engagement monitoring to prevent future issues.
- Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) is configured correctly.
- Suppression: Hard bounces should be immediately suppressed from your email lists.
Marketer view
Email marketer from email.geeks.chat advises monitoring which customers increased sends to Yahoo around when the TSS04 errors started. Look for new subscriber uploads or changes in sending behavior. Monitoring software is crucial to drill into the data to find customers that need removing from the network. Once identified, halting the problematic customer's sends should stop the TSS04 errors.
4 Dec 2021 - email.geeks.chat
Marketer view
Email marketer from mailsender.org suggests checking for any sudden spikes in sending volume. Also advises that a sender needs to ensure the recipient list is clean, permission-based, and well-segmented. They suggest that improving list hygiene and engagement metrics may reduce TSS04 issues.
10 May 2025 - mailsender.org
What the experts say
2 expert opinions
Troubleshooting Yahoo TSS04 errors often requires a deep dive into recent sending practices across shared IP pools. Key to resolution is maintaining a strong sender reputation, involving proper email authentication (SPF, DKIM, DMARC), low complaint rates, and active management of subscriber lists to remove inactive recipients. Analyzing complaint rates, spam trap hits, and changes in engagement levels across the pool can help pinpoint problematic senders or campaigns.
Key opinions
- Investigate Sending Practices: TSS04 errors are often vague, necessitating a review of recent sending practices across the shared IP pool.
- Maintain Strong Sender Reputation: A strong sender reputation is crucial for preventing TSS04 errors.
- Monitor Key Metrics: Actively monitor complaint rates, spam trap hits, and engagement levels.
- Identify Problematic Senders/Campaigns: Pinpoint problematic senders or campaigns contributing to the errors.
- Proper Authentication: Ensure proper email authentication (SPF, DKIM, DMARC) is in place.
- Active List Management: Actively manage subscriber lists to remove inactive or disengaged recipients.
Key considerations
- Deep Dive Required: Addressing TSS04 errors requires a thorough investigation into various factors.
- Proactive Reputation Management: Focus on proactive sender reputation management to avoid deliverability issues.
- Shared Pool Challenges: Managing shared IP pools requires careful oversight to ensure all users adhere to best practices.
Expert view
Expert from Word to the Wise, Laura Atkins, explains that TSS04 errors are often vague and require investigation into recent sending practices. She recommends reviewing complaint rates, spam trap hits, and changes in engagement levels across the shared IP pool. Identifying problematic senders or campaigns is crucial.
2 Mar 2025 - Word to the Wise
Expert view
Expert from Spam Resource explains that maintaining a strong sender reputation is critical for avoiding TSS04 errors. This includes ensuring proper authentication (SPF, DKIM, DMARC), keeping complaint rates low, and actively managing your subscriber list to remove inactive or disengaged recipients. Consistent monitoring of sender reputation metrics is essential.
5 Feb 2024 - Spam Resource
What the documentation says
5 technical articles
Troubleshooting TSS04 errors from Yahoo involves a multi-faceted approach. Initially, a waiting period of 24 hours is recommended as the error is often temporary. If the problem persists, investigation into potential spam-like activity is crucial. This includes checking bounce logs, sender reputation using tools like Sender Score, and ensuring proper authentication (SPF, DKIM, DMARC). Key factors influencing sender reputation are bounce rates, complaint rates, and spam trap hits, all of which require monitoring. Consistent sending frequency and low complaint rates are also vital. Hard bounces should be immediately suppressed due to invalid email addresses. Engaging with Yahoo's postmaster team with detailed information about sending practices and error messages is recommended for persistent issues.
Key findings
- Temporary Issue: TSS04 errors are often temporary; waiting 24 hours might resolve the issue.
- Spam-Like Activity: Yahoo uses TSS04 as a temporary block due to suspected spam-like activity.
- Bounce Logs: Check bounce logs for patterns to identify delivery issues.
- Sender Reputation: Verify sender reputation using tools like Sender Score.
- Authentication: Ensure proper authentication (SPF, DKIM, DMARC) is configured correctly.
- Reputation Metrics: Monitor bounce rates, complaint rates, and spam trap hits.
- Sending Frequency: Maintain a consistent sending frequency.
- Hard Bounce Suppression: Hard bounces should be suppressed immediately.
Key considerations
- Initial Waiting Period: Allow a 24-hour waiting period before initiating troubleshooting steps.
- Comprehensive Investigation: Conduct a comprehensive investigation into potential spam-like activity and sender reputation.
- Proactive Monitoring: Implement proactive monitoring of key metrics to maintain a healthy sender reputation.
- Postmaster Contact: Contact Yahoo's postmaster team for persistent issues after implementing best practices.
Technical article
Documentation from Microsoft states that to improve email deliverability, you must authenticate your email. Email authentication methods, such as DKIM and SPF, help verify that you own the domain from which the email was sent. It also recommends that you send emails with a consistent sending frequency, as well as ensure that you maintain a low complaint rate.
21 Jul 2023 - Microsoft
Technical article
Documentation from SparkPost states that a sender's reputation is primarily influenced by bounce rates, complaint rates, and spam trap hits. Monitoring these metrics is essential for understanding the health of your sending reputation and identifying potential issues that could trigger delivery errors like TSS04.
27 Mar 2025 - SparkPost
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