Summary
The sudden drop in Yahoo and MS CFLs can be attributed to several factors. These include changes in spam policies by Yahoo and MS potentially influenced by lower open rates, interruptions in feedback loops (FBLs), and algorithm updates by mailbox providers. Issues with sender reputation, encompassing IP/domain reputation, email content, authentication problems (SPF, DKIM, DMARC), high bounce rates, and spam complaints, are also significant contributors. Other factors include sending from un-warmed IPs, sudden email volume spikes, and aggressive spam filter settings. Maintaining list hygiene, monitoring sender reputation via tools like Google Postmaster Tools and Microsoft SNDS, and ensuring proper FBL processing are crucial for addressing these issues.
Key findings
- CFL Drops Confirmed: Multiple email marketers confirmed experiencing a sudden drop in Yahoo and MS CFLs.
- Spam Policy Changes: Yahoo's change in spam policy is a potential cause, interpreting emails as spam due to lower open rates.
- FBL Interruptions: Interruptions or incorrect processing of feedback loops can lead to a loss of visibility into user complaints.
- Sender Reputation Matters: Poor sender reputation, stemming from issues like high bounce rates or spam complaints, significantly impacts deliverability.
- Algorithm Updates: Changes in mailbox provider algorithms can lead to sudden drops in email deliverability.
- Authentication is Key: Lack of proper email authentication (SPF, DKIM, DMARC) makes emails more likely to be flagged as spam.
Key considerations
- Monitor Sender Reputation: Actively monitor sender reputation using tools like Google Postmaster Tools and Microsoft SNDS/JMRP.
- Implement Authentication: Ensure proper implementation of SPF, DKIM, and DMARC email authentication protocols.
- Maintain List Hygiene: Regularly clean email lists by removing unengaged subscribers and handling bounces.
- Warm-Up IPs: When introducing new IP addresses, gradually warm them up to establish a sending reputation.
- Process FBLs: Actively process feedback loops to identify and remove complainers from mailing lists.
- Targeted Content: Segment your email lists and send targeted content to engaged subscribers to improve reputation.
What email marketers say
14 marketer opinions
Several email marketers reported a sudden drop in Yahoo and Microsoft CFLs. Possible causes include changes in spam policies, lower email open rates, and alterations to mailbox provider algorithms. Broader issues such as IP blacklisting, poor sender reputation due to high bounce rates or spam complaints, and sending from un-warmed IP addresses can also contribute. In some cases, the issue was an interruption of Yahoo and Microsoft's Feedback Loops (FBLs).
Key opinions
- CFL Drops: Multiple marketers observed a sudden decrease in Yahoo and Microsoft CFLs.
- Spam Policy Changes: Yahoo may have altered its spam policies, leading to lower CFLs due to lower email open rates.
- FBL Issues: Interruptions in Yahoo and Microsoft's feedback loops (FBLs) were cited as a cause.
- Sender Reputation: Poor sender reputation, stemming from high bounce rates or spam complaints, can lead to deliverability problems.
- Algorithm Changes: Changes in mailbox provider algorithms can affect spam filtering.
Key considerations
- Monitor Reputation: Regularly monitor sender reputation using tools like Google Postmaster Tools and Microsoft SNDS.
- Authentication: Ensure proper email authentication with SPF, DKIM, and DMARC.
- List Hygiene: Maintain clean email lists to minimize bounce rates and spam complaints.
- Warm Up IPs: Gradually warm up new IP addresses before sending high volumes of email.
- Feedback Loops: Implement and monitor feedback loops (FBLs) to address recipient complaints promptly.
Marketer view
Email marketer from Quora shares that spam filters operate using algorithms that analyze various email attributes like sender reputation, content, and authentication. The user mentions if you are sending bulk emails, make sure you authenticate your email using SPF and DKIM to improve deliverability and avoid being flagged as spam.
8 Jul 2024 - Quora
Marketer view
Email marketer from EmailAnalytics Blog explains that sudden drops in deliverability can stem from various sources, including changes in mailbox provider algorithms, increased spam complaints, or IP blacklisting. It suggests monitoring sender reputation, warming up IP addresses, and authenticating emails.
2 Apr 2023 - EmailAnalytics Blog
What the experts say
2 expert opinions
Experts emphasize the importance of feedback loops (FBLs) in maintaining email list hygiene and sender reputation. Interruptions or incorrect processing of FBLs can lead to a loss of visibility into user complaints, hindering senders' ability to manage their lists effectively and potentially increasing spam filtering.
Key opinions
- FBL Importance: Feedback loops are critical for senders to identify and remove complainers from their email lists.
- Impact of FBL Issues: Interruptions or incorrect processing of FBL data negatively impacts senders' ability to maintain list hygiene and manage sender reputation.
- Visibility Loss: Problems with FBLs can lead to a loss of visibility into user complaints.
Key considerations
- Monitor FBLs: Actively monitor feedback loops to identify and address spam complaints.
- Ensure Proper Processing: Ensure that FBL data is processed correctly to maintain accurate complaint information.
- Maintain List Hygiene: Use FBL data to remove complainers from email lists and maintain a clean, engaged audience.
- Protect Sender Reputation: Proactively manage sender reputation by addressing issues identified through FBLs to avoid increased spam filtering.
Expert view
Expert from Word to the Wise (Laura Atkins) explains that if FBLs are not processed correctly, senders lose visibility into user complaints, which impacts their ability to manage sender reputation and can lead to increased spam filtering.
15 May 2025 - Word to the Wise
Expert view
Expert from Spam Resource (John Levine) explains that feedback loops provide senders with data on spam complaints, allowing them to remove complainers from their lists. The expert mentions that interruptions to FBL data can impact senders' ability to maintain list hygiene.
1 Nov 2023 - Spam Resource
What the documentation says
4 technical articles
Documentation from multiple sources suggests that a sudden drop in CFLs or email deliverability can be attributed to issues with IP/domain reputation, email content, authentication problems, changes in email provider algorithms, or spam filtering techniques. Maintaining a clean email list, using proper authentication (SPF, DKIM, DMARC), keeping spam rates low, and monitoring sender reputation through tools like Google Postmaster Tools and Microsoft SNDS are crucial.
Key findings
- Reputation Issues: Poor IP and domain reputation can lead to emails being marked as spam.
- Authentication: Proper email authentication (SPF, DKIM, DMARC) is essential for deliverability.
- Algorithm Changes: Email provider algorithm and spam filtering technique changes can impact deliverability.
- List Hygiene: Maintaining a clean and engaged email list improves sender reputation.
- Spam Rate: Keeping spam rates low and avoiding sudden spikes is crucial.
Key considerations
- Monitor Reputation: Regularly monitor sender reputation using tools like Google Postmaster Tools and Microsoft SNDS/JMRP.
- Authenticate Email: Implement SPF, DKIM, and DMARC for email authentication.
- Clean Email Lists: Regularly clean email lists by removing unengaged subscribers.
- Segment Lists: Segment email lists to send targeted content to engaged subscribers.
- Monitor Feedback Loops: Check feedback loops and reputation monitoring tools for issues.
Technical article
Documentation from Microsoft Support explains that if your emails are being marked as spam, it could be due to issues with your IP address reputation, domain reputation, content, or authentication. They detail how to check your sender score and use tools like SNDS and JMRP to monitor your sending reputation with Microsoft.
26 Mar 2022 - Microsoft Support
Technical article
Documentation from Google Postmaster Tools explains that to prevent mail to Gmail users from being blocked, senders must authenticate their email with SPF, DKIM, and DMARC. Google documentation also explains that senders should keep their spam rate reported in Postmaster Tools below 0.10% and avoid sudden spikes. Ensure sending IPs have valid forward and reverse DNS records (PTR records).
28 Feb 2025 - Google Postmaster Tools
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