Why is Microsoft suddenly making negative changes to sender reputation?

Key findings

• Shared pools: There is a strong indication that Microsoft has increased its scrutiny on emails originating from shared IP pools, potentially leading to more frequent reputation issues for senders utilizing these services.
• Sudden changes: Many senders have reported experiencing sudden and negative changes to their sender reputation with Microsoft, often without clear prior warning or explanation.
• Support mitigation: While Microsoft support can sometimes help mitigate these issues for legitimate senders, success appears to be more likely for those with stronger individual reputations (e.g., dedicated IPs) compared to shared pools.
• Squeaky clean requirement: Microsoft seems less inclined to offer mitigation for senders who are not maintaining extremely high standards of email hygiene and engagement, suggesting a stricter baseline for positive reputation.

Key considerations

• Monitor closely: Keep a vigilant eye on your Microsoft deliverability metrics, including bounces and inbox placement, to identify any sudden shifts.
• Review sending practices: Regularly audit your list quality, engagement levels, and complaint rates to ensure your sending practices are impeccable. This includes a careful look at how your domain reputation might be affected.
• Dedicated vs. shared IPs: If you are using shared IP pools and experiencing consistent issues, consider the feasibility of transitioning to dedicated IPs, which often provide more control over your sender reputation.
• Proactive engagement: Engage proactively with Microsoft's sender support if issues arise, providing clear evidence of your compliant sending practices.

Key opinions

• Frustration with delays: Many marketers report new and frustrating delays or outright blocks from Microsoft domains, even for senders who previously had good standing.
• Perception of unhappiness: There's a widespread feeling that Microsoft has become particularly unhappy with shared IP pools, leading to disproportionate impacts on users of these services.
• Rolling issues: Some marketers have observed rolling deliverability issues over several weeks, suggesting an ongoing adjustment rather than a one-off event.
• Outlook junk filtering: Marketers are seeing more emails land in the junk folder, which indicates heightened sensitivity to Spam Confidence Level (SCL) and Bulk Complaint Level (BCL) scores.

Key considerations

• List hygiene: Continuously clean your email lists to remove inactive or problematic addresses to minimize spam complaints and maintain high engagement.
• Content quality: Ensure your email content is relevant, engaging, and free of typical spam triggers. Personalization and value are key.
• Sender authentication: Verify your DMARC, SPF, and DKIM records are correctly configured and aligned, as Microsoft heavily relies on these for sender validation. Our guides on authentication can help.
• User engagement: Focus on driving positive engagement (opens, clicks, replies) and reducing negative signals (spam complaints, unsubscribes) to build a robust sender reputation.

Key opinions

• Shared pool challenges: Experts confirm that Microsoft appears to be increasingly critical of traffic from shared IP pools, suggesting these environments now face higher scrutiny and potential negative reputation impacts.
• Sudden reputation shifts: There's an agreement that Microsoft is indeed making sudden negative changes to reputation for some senders, even those with historically good standing.
• Mitigation difficulty: For senders not maintaining extremely squeaky clean sending practices, obtaining mitigation or delisting assistance from Microsoft seems to be increasingly challenging.
• Behavioral filtering: Microsoft heavily relies on user engagement and behavioral metrics to determine inbox placement, making it crucial for senders to maintain healthy engagement rates.

Key considerations

• Engagement strategy: Prioritize strategies that boost positive user engagement and minimize spam complaints. This includes double opt-in and clear unsubscribe options.
• Authentication standards: Ensure full compliance with email authentication protocols like SPF, DKIM, and DMARC. These are foundational for building trust with Microsoft's filters and mitigating hidden SPF DNS timeouts.
• Reputation management: Implement robust monitoring for your IP and domain reputation, including blocklist checks (or blacklist checks), to quickly identify and address issues. See our guide on blocklists.
• Provider relations: Maintain a good relationship with your email service provider (ESP) or internal team, ensuring they are aware of and responsive to Microsoft's evolving requirements.

Key findings

• Authentication emphasis: Microsoft consistently stresses the importance of robust email authentication (SPF, DKIM, DMARC) for all senders, as these protocols help verify legitimacy and prevent impersonation.
• Complaint rates: Documentation often points to high complaint rates (spam reports) as a primary indicator of poor sender reputation, leading to immediate filtering actions.
• Volume and cadence: Microsoft's systems monitor sending volume and cadence for unusual spikes, which can trigger temporary blocks or reputation degradation if not justified by list growth.
• Feedback loops (FBLs): Microsoft's Sender Information for Outlook.com provides details on how FBLs work, enabling senders to receive complaint data and improve their lists based on user feedback.

Key considerations

• Adhere to new requirements: Stay updated on Microsoft's new sender requirements, which often align with broader industry efforts to enhance email security and reduce unsolicited mail.
• Implement FBLs: Register for and actively monitor Microsoft's JMRP (Junk Mail Reporting Program) to receive spam complaints directly, allowing for prompt list clean-up.
• Check compliance regularly: Use tools and resources to verify your DMARC, SPF, and DKIM records are correctly set up and in compliance with Microsoft's expectations. Our guide on fixing common DMARC issues can be helpful.
• Maintain positive metrics: Focus on maintaining low bounce rates, low complaint rates, and high positive engagement to positively influence your Sender Reputation Data (SRD) with Microsoft.