Summary
Despite a 'green' SNDS (Smart Network Data Services) status, transactional email deliverability issues to Microsoft (specifically Office 365) are multifactorial and often stem from elements outside of SNDS's purview. SNDS data primarily reflects Outlook.com, not all Microsoft email services. Microsoft employs complex filtering systems incorporating user complaints, content analysis, and sender reputation metrics beyond SNDS, making a 'green' SNDS status insufficient. User spam reports are a potent negative signal, outweighing a positive SNDS score. Address acquisition processes, data sanitization, authentication (SPF, DKIM, DMARC), list hygiene, content spam triggers, shared IP reputation, sending volume, and IP warm-up strategies all affect deliverability. Blocklisting, SMTP compliance, and external reputation services also play roles. A holistic approach emphasizing user feedback, engagement, compliance, and proactive reputation management is required.
Key findings
- SNDS Scope: SNDS data limited to Outlook.com, not comprehensive for all Microsoft services.
- Complex Filtering: Microsoft uses multifactorial filtering, beyond SNDS.
- User Feedback Dominates: User spam reports strongly influence filtering.
- Acquisition Matters: Problems in address acquisition processes impact delivery.
- Data Quality Important: Data sanitization at collection point.
- Shared IP Risk: Shared IPs are susceptible to the behavior of other senders.
- Content Issues: Spam triggers in content negatively affect deliverability.
- Volume Affects Delivery: Sudden volume increases are negatively affecting deliverability.
- Reputation Broad: Your reputation extend beyond just SNDS.
- Authentication is key: SPF, DKIM and DMARC setup is critical.
Key considerations
- SNDS Understanding: Understand SNDS is not a complete picture.
- Feedback Loops: Engage MS feedback loops to manage reputation
- User Engagement: Focus on improving engagement metrics to reduce spam reporting
- Improve Acquisition: Improve address acquisition processes.
- Shared IP Monitoring: Monitor shared IP address health.
- Content Review: Review email content for spam triggers and coding best practices.
- Gradual Volume: Ensure volume ramp-up is gradual.
- Multi-Platform Monitoring: Monitor your reputation across multiple platforms.
- Compliance: Ensure SMTP Compliance.
- Warm Up Strategy: Implement IP warm-up strategy
- DMARC: Implement DMARC to ensure authentication
What email marketers say
9 marketer opinions
Despite a 'green' status in SNDS (Smart Network Data Services), transactional email deliverability issues to Microsoft (specifically Office 365) can arise due to a multitude of factors. These factors encompass Microsoft's internal reputation systems (separate from SNDS), user-driven spam filtering, shared IP reputation issues, problems with list hygiene, triggers in email content, sending volume and lack of IP warming strategies, and overall sender reputation which extends beyond SNDS. User feedback, bounce rates and spam complaints are heavily weighted by Microsoft. Thus, a holistic approach to email deliverability is required.
Key opinions
- Internal Reputation: Microsoft uses internal reputation systems beyond SNDS.
- User-Driven Filtering: User spam reports significantly impact deliverability, overriding SNDS.
- Shared IP Issues: Shared IP addresses are vulnerable to the actions of other senders.
- List Hygiene Importance: Poor list hygiene, high bounce/complaint rates affect delivery.
- Content Triggers: Spam triggers in email content cause deliverability issues.
- Volume Throttling: Microsoft may throttle volume increases, irrespective of SNDS.
- Reputation Extends Beyond SNDS: Other reputation services influence Microsoft filtering decisions.
- IP Warm-up: New IPs require a warm-up strategy to avoid filtering.
Key considerations
- Proactive Reputation Management: Proactively manage your sending reputation with Microsoft feedback loops.
- Engagement Metrics: Focus on improving engagement metrics to enhance O365 deliverability.
- Monitor Bounce/Complaint Rates: Actively monitor bounce rates and spam complaints to maintain good IP reputation.
- SMTP Standards Compliance: Ensuring proper SMTP standards compliance.
- Shared IP Monitoring: Monitor shared IP reputation closely.
- Email Content Review: Regularly review email content for spam triggers and coding issues.
- Regular List Cleaning: Clean your email list regularly to minimize bounces and complaints.
- Gradual Volume Ramp-Up: Gradually ramp up sending volume to avoid throttling.
- Monitor Reputation Services: Monitor your reputation across multiple platforms, not just SNDS.
- IP Warmup Strategy: Implement a proper warm-up strategy for new IP addresses.
Marketer view
Email marketer from StackOverflow explains that If using shared IP addresses, a sudden spike in bounce rates and spam complaints from other senders on the same IP can affect your deliverability to Microsoft, regardless of your own SNDS standing. Recommend monitoring shared IP reputation closely.
16 Oct 2024 - StackOverflow
Marketer view
Email marketer from Email Vendor Guide explains that Microsoft uses its own internal reputation systems separate from SNDS. Even with a good SNDS reputation, internal factors can impact deliverability to Office 365 users. They recommend proactively managing your sending reputation specifically with Microsoft through their feedback loops and reporting mechanisms.
16 Sep 2022 - Email Vendor Guide
What the experts say
5 expert opinions
Despite a 'green' SNDS (Smart Network Data Services) status, transactional email deliverability issues to Microsoft (specifically Office 365) arise due to factors beyond SNDS data. SNDS data doesn't reflect O365 accounts and therefore is not useful for deliverability issues relating to them. Microsoft utilizes complex filtering systems incorporating user complaints, content analysis, and sender reputation data beyond SNDS. Aggressive filtering due to user-generated spam reports is a significant factor, as SNDS doesn't account for individual user complaints. Address acquisition processes, data sanitization, and opt-in procedures play crucial roles. Problematic address acquisition or failing to sanitise data, O365 users can easily mark emails as spam, impacting the sender's reputation. These factors necessitate proactive reputation management, focusing on improving address acquisition, data sanitisation, opt-in processes and high quality content.
Key opinions
- SNDS Limitations: SNDS data is not reflective of O365 accounts and data.
- Complex Filtering: Microsoft employs complex filtering systems beyond SNDS data.
- User Complaints Matter: User-generated spam reports significantly impact deliverability.
- Address Acquisition is Key: Problems in address acquisition process impact deliverability.
- Data Sanitisation is Key: Lack of data sanitisation is impacting deliverability.
Key considerations
- Address Acquisition Review: Review and improve address acquisition processes.
- Opt-in Processes: Focus on opt-in processes to minimize spam complaints.
- Data Sanitisation: Implement data sanitisation at data collection point.
- Proactive Management: Practice proactive reputation management due to SNDS limitations.
Expert view
Expert from Spam Resource explains that Microsoft's filtering systems are complex and use a variety of signals, including user complaints, content analysis, and sender reputation data beyond what is shown in SNDS. A green SNDS status does not override negative signals from these other systems.
18 Dec 2023 - Spam Resource
Expert view
Expert from Email Geeks explains if the issue keeps happening, there is likely a problem in the address acquisition process, and emphasizes that users on O365 can easily mark emails as spam. This impacts reputation at Microsoft, but this information is not available through SNDS or JMRP messages, requiring different reputation management strategies than consumer domains.
23 Jan 2025 - Email Geeks
What the documentation says
5 technical articles
Transactional email deliverability issues to Microsoft, even with a 'green' SNDS status, stem from several factors not fully reflected by SNDS. SNDS primarily covers Outlook.com data, not all Microsoft email services. Being on blocklists (user or system-generated) independently impacts deliverability. Non-compliance with SMTP standards (RFC 5321 etc.) leads to flagging. DMARC policy failures cause blocks, irrespective of SNDS. User spam reports are a significant negative signal to Microsoft's filters. Therefore, compliance, authentication and user-feedback is key to ensuring deliverability.
Key findings
- SNDS Scope Limited: SNDS data mostly covers Outlook.com, not all Microsoft services.
- Blocklists Impact: Blocklisting by users or systems affects deliverability.
- SMTP Compliance Crucial: Non-compliance with SMTP standards leads to flagging.
- DMARC Failures Block: DMARC policy failures result in blocked emails.
- User Spam Reports: End-user spam reporting heavily affects deliverability.
Key considerations
- Monitor Blocklists: Monitor blocklist status regularly.
- Ensure SMTP Compliance: Ensure full SMTP standards compliance.
- Implement Strict DMARC: Properly implement DMARC policies.
- Reduce Spam Reporting: Work to reduce user-generated spam reports.
Technical article
Documentation from Microsoft explains that end-user spam reporting (clicking 'This is Spam' in Outlook) is a strong signal for Microsoft's filtering systems. Even with a green SNDS status, a high rate of spam reports will negatively impact deliverability.
10 May 2022 - Microsoft
Technical article
Documentation from Microsoft explains that a common reason for transactional email deliverability issues to O365 is being placed on a blocked sender list, either by individual users or by Microsoft's automated systems. These lists are separate from SNDS data.
6 Jul 2021 - Microsoft
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