Why does Microsoft SNDS data contradict email deliverability during IP warming?

Key findings

• SNDS vs. Inbox Placement: SNDS provides data on IP reputation and policy compliance (often indicated by color codes), but this does not directly translate to inbox placement rates. A 'green' status means Microsoft is accepting your mail, not necessarily placing it in the inbox.
• New IP Scrutiny: During IP warming, new IP addresses are often treated with suspicion by Microsoft and other Mailbox Providers (MBPs), leading to initial placement in the spam folder even if they are not explicitly blocked or blacklisted.
• Engagement Metrics: Real-world engagement metrics, such as open rates, click-through rates, and complaint rates, provide a more accurate picture of actual deliverability than SNDS status during the warming phase.
• Multifaceted Filtering: Microsoft's filtering algorithms consider numerous factors beyond just IP reputation, including content, sender behavior, and the historical relationship with recipients.

Key considerations

• Holistic Monitoring: Do not rely solely on SNDS. Complement it with robust internal analytics, seed list testing, and other deliverability tools to get a complete view.
• Patience During Warmup: Understand that IP warming is a gradual process. Initial lower open rates and higher spam placement at Microsoft are normal until a positive sending reputation is established.
• Proactive Engagement: Consider contacting Microsoft's support team proactively to inform them of your IP warming plans and expected volumes, as this may help ease filtering.
• Focus on Engagement: Prioritize sending highly engaging content to your most active subscribers during warming to build a strong positive reputation. Learn how to improve deliverability to Outlook addresses.

Key opinions

• SNDS Colors are Misleading: Many marketers believe the green/yellow/red color codes in SNDS do not accurately reflect inbox placement, especially for new or warming IPs.
• Spam Placement is Expected: It is widely observed that new IPs will likely experience nearly 100% spam placement at Microsoft during the initial warming period, regardless of SNDS status.
• Reliance on Engagement Metrics: Marketers emphasize that actual engagement data, like open rates, is the only reliable indicator of deliverability performance, especially when compared to other mailbox providers.
• Silent Blocking: Some report that Microsoft may silently drop or redirect emails to the spam folder without generating explicit bounces, making it harder to diagnose issues via traditional bounce logs.

Key considerations

• Verify with Internal Data: Always cross-reference SNDS data with your own engagement metrics (opens, clicks, complaints) and deliverability testing tools.
• Analyze Bounce Logs: Request detailed delivery and bounce logs from your Email Service Provider (ESP) to understand how Microsoft is responding to your sends. This helps troubleshoot Microsoft deliverability issues.
• Adjust Sending Volumes: If deliverability remains low, consider pulling back sending volumes to levels that previously yielded better placement and slowly re-increase.
• Escalation Paths: Be aware of Microsoft's potential filtering escalation paths (bulk folder, silent dropping, rate limiting, blocking, IP blocking, router blocking) and how to respond at each stage. Understanding how to solve Microsoft deliverability issues is key.

Key opinions

• SNDS is Informative, Not Definitive: Experts agree that SNDS provides useful filter colors, but these are not the only factors influencing Microsoft's placement decisions. A green status indicates acceptance, not guaranteed inbox delivery.
• Proactive Communication Helps: Contacting the Microsoft team upfront to inform them about IP warming and anticipated volumes can lead to eased filtering and fewer problems during the warmup phase.
• Guilty Until Proven Innocent: During IP ramp-up, new IPs are generally considered suspicious until they establish a positive sending reputation through consistent good practices.
• Own the Communication: If you are aware of your email infrastructure, you can contact Microsoft directly; there's no inherent benefit in having your ESP make the mitigation request.

Key considerations

• Monitor Bounces for Rate Limiting: Actively check for soft bounces, as these can indicate Microsoft is rate limiting your emails, which is a common issue during warmup. This can help resolve Microsoft email blocks.
• Prepare for Proactive Contact: When contacting Microsoft, be ready to provide details on anticipated volume, links to your email practices (e.g., anti-spam policy), and sending dates.
• Webform Usage: The standard Microsoft support webform is typically sufficient for these proactive requests.
• Expect Initial Challenges: Even with proactive steps, some initial inbox placement challenges at Microsoft are to be expected. Consistency and adherence to best practices will gradually build trust, even if SNDS colors remain red.

Key findings

• SNDS Purpose: SNDS is designed to provide registered senders with insights into their IP reputation, allowing them to self-diagnose and address potential issues that could lead to filtering.
• Reputation Building: Microsoft, like other ISPs, builds trust with sending IPs over time. A new IP has no established reputation, so it naturally undergoes stricter filtering until it proves itself as a legitimate sender.
• Multiple Filtering Layers: Deliverability is influenced by a combination of IP reputation, domain reputation, content quality, sender authentication (SPF, DKIM, DMARC), and recipient engagement.
• IP Warming Best Practices: Official documentation and best practices universally recommend a gradual IP warming process to build sender reputation and establish trust with major mailbox providers.

Key considerations

• SNDS as a Diagnostic: View SNDS as a diagnostic tool for potential issues (e.g., high complaint rates, blocklist activity) rather than a direct indicator of inbox placement. For broader insights, consider technical solutions for email deliverability.
• Adherence to Policies: Ensure full compliance with Microsoft's mail policies and terms of service, including proper authentication (SPF, DKIM, DMARC) and consent-based sending.
• Expect Initial Challenges: Understand that during IP warming, it's standard for new IPs to face initial filtering. This is a normal part of the trust-building process before consistent inbox placement is achieved. This is a common email deliverability issue.
• User Engagement Focus: Microsoft's systems heavily weigh user engagement signals. Positive interactions are critical for improving sender reputation and inbox placement over time.