How did Yahoo update their FBL ARF format and how did it impact ESPs?

Key findings

• Undisclosed changes: Yahoo updated its FBL ARF format without prior announcement, catching ESPs off guard.
• Data disruption: Many ESPs experienced a sudden cessation of Yahoo complaint data, with dashboards showing zero complaints.
• Format abnormalities: The new ARF format appeared unusual, with original headers stripped and received headers reportedly mashed together, potentially exposing internal Yahoo information.
• MTA incompatibility: While some Mail Transfer Agents (MTAs) could process the new format, others, such as GreenArrow and Momentum, could not.
• Rapid rollback: Yahoo quickly acknowledged the issue and rolled back the changes, restoring FBL reporting within a day, though with duplicate reports for the affected period.

Key considerations

• Monitoring is key: Continuous monitoring of FBL data is essential for ESPs to detect such unannounced changes quickly and minimize negative impacts on deliverability.
• System adaptability: ESPs need flexible complaint processing systems that can quickly adapt to minor format variations or require minimal development to handle unexpected changes.
• Communication importance: The incident underscores the need for clear and proactive communication from major Mailbox Service Providers (MSPs) like Yahoo regarding any changes to their FBL (Feedback Loop) or ARF (Abuse Reporting Format) specifications, particularly with the new Gmail and Yahoo sender requirements for 2024.
• Data integrity: Ensuring the integrity of FBL data is paramount, as it directly influences a sender's ability to maintain a healthy sender reputation and avoid blacklists.
• Impact on suppressions: A temporary loss of FBL data can hinder the timely suppression of complaining users, potentially leading to increased spam complaints and a degraded sender reputation. You can learn more about Yahoo's requirements in their postmaster blog.

Key opinions

• Unexpected disruption: Many marketers were caught off guard by the unannounced format change, leading to a sudden halt in Yahoo complaint data processing.
• System compatibility issues: Different MTAs had varying success in processing the new format, with some failing entirely, highlighting system-specific vulnerabilities.
• Data integrity concerns: The altered FBLs, with stripped and mashed headers, raised concerns about the integrity and usefulness of the data for identifying problematic sends.
• Operational impact: The inability to process FBLs directly impacted suppression list updates and overall deliverability monitoring for affected ESPs.
• Call for communication: There was a strong sentiment among marketers for Yahoo to provide advance notice for any significant changes to their FBL format, given its critical role.

Key considerations

• Review FBL processing: ESPs and senders should regularly review their systems' ability to process FBL data, especially after any unannounced changes from major ISPs. This impacts how spam complaints from Google and Yahoo inform ESPs.
• Automated system resilience: Build or use automated systems for FBL processing that are robust enough to handle minor format deviations or that can be quickly updated. Some feedback loops for Google and Oath also have unique practices.
• Contingency planning: Have contingency plans in place for when critical data feeds are disrupted, such as manual review processes or alternative reputation metrics.
• Industry collaboration: Engage in industry forums and communities to share information and solutions quickly when unexpected issues arise, as seen in the timely response to this Yahoo change, as highlighted by EmailExpert.
• Prioritize suppression: Ensure that even during FBL disruptions, mechanisms for identifying and suppressing problematic senders remain active to protect sender reputation.

Key opinions

• Prompt identification: Experts quickly noticed and alerted the community about the unannounced Yahoo FBL ARF format update.
• Format analysis: Initial analysis revealed unusual header stripping and mashing, leading to speculation about whether the change was intentional or a mistake.
• Acknowledgement and rollback: Yahoo's representatives acknowledged the differences in the reports and advised against rushing changes, later confirming a rollback of the update.
• Community value: The rapid communication within expert communities proved vital in quickly identifying the issue and prompting a resolution from Yahoo.
• Impact on processing: Experts noted that the format change specifically impacted how various MTAs and FBL processing systems interpreted and utilized the complaint data.

Key considerations

• Maintain vigilance: Experts recommend continuous monitoring of FBL data feeds for any anomalies, as unannounced changes can severely impact deliverability metrics and sender reputation.
• Flexible parsing: Systems designed to parse FBLs should be built with flexibility to handle unexpected format variations, reducing the need for emergency re-coding.
• Official communication channels: Relying on official postmaster blogs and direct communication channels from ISPs is crucial for staying informed about any planned or accidental changes. For example, Sweego provides details on FBLs.
• Understand ARF details: A deep understanding of the ARF (Abuse Reporting Format) standard is essential for ESPs, including how ESPs collect Yahoo FBL data using double DKIM signing.
• Impact on blocklists: Disruptions in FBL data can have a cascading effect, potentially leading to increased spam complaints and a higher risk of being added to email blocklists or blacklists if problematic sending patterns are not identified and addressed quickly.

Key findings

• Standardized format: ARF (Abuse Reporting Format) is a widely recognized standard for reporting email abuse and spam complaints.
• FBL purpose: Feedback Loops (FBLs) serve as a crucial communication channel for Mailbox Service Providers (MSPs) to inform Email Service Providers (ESPs) about user complaints.
• Reputation management: Proper utilization of ARF data is essential for managing sender reputation, suppressing complainers, and improving inbox placement.
• Authentication importance: Many FBL programs, including Yahoo's, require strong email authentication (e.g., DKIM-signing) to ensure the legitimacy of the reported complaints.
• Variations among providers: While ARF is a standard, some providers may offer aggregated data or alternative reporting methods, emphasizing the need to understand each ISP's specific implementation.

Key considerations

• ARF parsing capabilities: ESPs must ensure their systems are capable of accurately parsing and processing ARF data according to the current specifications of various ISPs. This is especially true for Yahoo's Complaint Feedback Loop (CFL).
• Stay updated: Regularly check postmaster sites and official documentation from major ISPs (e.g., Yahoo, Gmail) for updates to FBL programs and formats, as highlighted by Mailercloud Blog.
• Implement DMARC: Ensure proper email authentication, including SPF, DKIM, and DMARC, as these are often prerequisites for FBL enrollment and provide crucial context for complaint data. Learn how to troubleshoot DMARC reports from Google and Yahoo.
• Data actionability: Focus not just on receiving FBL data, but on having automated processes to act upon it promptly, by suppressing complainers and analyzing campaign performance.