Summary
New IP addresses typically display a 'red' status in Microsoft's Sender Network Data Services (SNDS) during the warming phase because they start with no established sending history or reputation. Microsoft's systems are designed to be highly cautious, requiring a substantial and consistent pattern of legitimate sending, low spam complaints, and positive user engagement over time to build trust. The deliberate low sending volumes during warming can make this reputation-building process slow, and any negative signals, even minor ones like a few spam complaints, can significantly delay the IP from moving out of a 'red' or neutral classification.
Key findings
- Blank Slate Reputation: New IPs begin with no historical sending data, making them initially unknown or even suspicious to ISPs like Microsoft.
- Time-Sensitive Process: Building a positive sender reputation is a slow, gradual process that requires sustained, consistent good sending practices.
- ISP Caution: Microsoft's systems are inherently cautious with unknown IPs, prioritizing user protection, and will only elevate reputation after observing significant clean sending.
- Negative Signals Amplify: Even minimal spam complaints or spam trap hits during the sensitive warming period can heavily damage reputation and prolong a 'red' status.
- Low Volume Impact: The controlled, low sending volume characteristic of IP warming naturally slows the accumulation of sufficient positive data needed to quickly establish trust.
Key considerations
- SNDS as an Indicator: While 'red' in SNDS indicates a poor or unknown reputation, it doesn't always directly correlate to mail being blocked, and may simply reflect a lack of established history.
- Focus on Deliverability Metrics: Prioritize monitoring actual inboxing rates and engagement over solely relying on SNDS color as the primary measure of success.
- Patience and Consistency: Recognize that reputation building takes time, and sustained, high-quality sending is crucial for moving past initial 'red' statuses.
- Extreme Cleanliness: Maintain exceptionally clean lists and sending practices during warming to avoid any negative signals that could derail reputation building.
- Escalation if Persistent: If IPs remain red without improvement after about a month of consistent, good sending, consider opening a support ticket with Microsoft.
What email marketers say
13 marketer opinions
The 'red' indicator in Microsoft's Sender Network Data Services (SNDS) for new IP addresses during warming is a common observation, stemming from the fact that these IPs initially possess no established sending history. ISPs, including Microsoft, adopt a highly cautious approach to unknown senders, demanding sustained evidence of legitimate and engaging email traffic to build trust. The low sending volumes inherent to the warming process contribute to this prolonged 'red' status, as a positive reputation is built gradually over time. Furthermore, any early negative feedback, even minor spam complaints, can significantly hinder an IP's progression toward a favorable reputation.
Key opinions
- Lack of History: New IP addresses begin with a blank slate, lacking any historical sending data or established reputation, which makes them 'unknown' to ISPs like Microsoft.
- ISP Caution: Microsoft's systems are designed to be highly cautious with new IPs, requiring sustained evidence of legitimate and engaging email traffic before assigning a positive reputation.
- Slow Reputation Build: The controlled, low sending volumes during the warming phase naturally slow down the accumulation of positive engagement data, prolonging the 'red' status.
- High Sensitivity to Negatives: Even a small number of spam complaints or hits to spam traps can severely derail a nascent IP reputation, causing it to remain 'red' in SNDS for an extended period.
- Demand for Engagement: IPs need to demonstrate consistent sending of desired content to an active and engaged audience to accumulate the positive metrics required for trust building.
Key considerations
- Patience is Paramount: Understand that reputation building, and thus the shift from a 'red' SNDS status, is a slow and gradual process that requires significant patience.
- Rigorous List Hygiene: Strictly maintain a clean mailing list and actively avoid any spam traps or complaints, as even minor issues can severely impede reputation during warming.
- Consistent Sending Schedule: Adhere to a consistent, gradual increase in sending volume, as sporadic or inconsistent sending can hinder positive reputation accumulation.
- Monitor Key Metrics: Beyond SNDS indicators, closely track actual deliverability rates, open rates, click-through rates, and complaint rates to gauge warming progress effectively.
- Consider Microsoft Support: If IP addresses remain persistently 'red' in SNDS after a month of consistent and proper warming, it may be advisable to open a support ticket with Microsoft.
- Explore Pre-Warming: Some marketers find success with 'pre-warming' strategies, starting with highly engaged, whitelisted Microsoft addresses to build initial trust before broader volume increases.
Marketer view
Email marketer from Email Geeks explains that Microsoft IP warming takes time and suggests opening a ticket if no change after a month of consistent sending.
16 Aug 2024 - Email Geeks
Marketer view
Email marketer from Email Geeks shares their strategy for battling persistent Microsoft IP warming issues, which includes attempting "pre-warming" with whitelisted Microsoft addresses before opening to auto-warming for all recipients, emphasizing a lower risk tolerance for their important product transactional emails.
7 Apr 2022 - Email Geeks
What the experts say
3 expert opinions
New IP addresses often remain 'red' in Microsoft's Sender Network Data Services (SNDS) during the warming period because SNDS is a reactive reporting tool that reflects an IP's current reputation rather than an immediate predictor of deliverability. At the deliberately low volumes used for warming, Microsoft's systems do not gather sufficient consistent data to establish a strong, positive sender reputation. Experts highlight that SNDS colors were historically not always reliable indicators of true inboxing, emphasizing that a 'red' status doesn't necessarily mean mail is being blocked, but rather that Microsoft has not yet accumulated enough positive signals to grant the IP a favorable standing.
Key opinions
- SNDS Is Reactive: Microsoft's Sender Network Data Services (SNDS) is a reactionary tool, meaning it reflects an IP's current reputation based on observed sending patterns rather than predicting future deliverability.
- Historical Unreliability: Experts note that SNDS color indicators were historically not always reliable in correlating to actual inbox placement, although their accuracy may have improved over time.
- Data Scarcity Impacts Rating: During the low-volume phase of IP warming, Microsoft often lacks sufficient, consistent positive data to establish a good reputation, which can keep the IP's status red.
- Red Doesn't Imply Blocks: A 'red' status in SNDS for a new IP does not automatically mean mail is being blocked; it often indicates a lack of established trust or sufficient data for Microsoft to assign a positive reputation.
- Lack of Established Trust: New IPs remain red because they start with no established history, and Microsoft's filters require time and consistent, clean sending to build the necessary trust to change the reputation indicator.
Key considerations
- Prioritize Actual Deliverability: Focus on the actual inboxing rates and mail flow rather than solely relying on the SNDS color, as the tool's indicators may not always perfectly reflect true deliverability.
- SNDS as a Reporting Tool: Understand that SNDS functions primarily as a reporting tool reflecting current reputation, rather than a direct control mechanism for email flow or an immediate predictor of blocks.
- Patience and Consistency Required: Recognize that accumulating sufficient positive data for Microsoft to change an IP's status from red to green demands consistent, good sending practices over an extended period.
- Don't Over-Interpret Colors: While SNDS provides valuable insights, avoid over-interpreting the color status, especially considering historical instances where the colors were not always reliable indicators of true inbox placement.
- Focus on Data Accumulation: The primary goal during warming is to consistently send clean, wanted mail, allowing Microsoft's systems to accumulate enough positive data to establish a trusted reputation for the new IP.
Expert view
Expert from Email Geeks responds by questioning the actual inboxing rate and explains that for a long time, the SNDS colors were not reliable indicators of delivery, stating "the colors are a lie". She notes it might be better correlated now but emphasizes past unreliability.
27 Apr 2023 - Email Geeks
Expert view
Expert from Spam Resource explains that new IPs often appear red in Microsoft SNDS during warming because SNDS is a reactionary tool reflecting current reputation, and low volume or initial sending patterns may not yet align with Microsoft's filters. He notes that red doesn't necessarily indicate blocks if mail is flowing well, and even clean IPs can be red due to a lack of established reputation.
28 Mar 2022 - Spam Resource
What the documentation says
5 technical articles
New IP addresses often remain 'red' in Microsoft's Sender Network Data Services (SNDS) during the warming period because they begin with no established trust. Microsoft's systems initiate with a cautious, neutral, or even negatively weighted stance, demanding a substantial and consistent history of legitimate sending. This includes sending only to valid users, fostering high engagement, and crucially, maintaining an exceptionally low rate of spam complaints. Even minor negative signals during this sensitive phase can heavily influence and prolong the 'red' status, as Microsoft prioritizes protecting its users from unwanted mail, quickly flagging any suspicious activity.
Key findings
- Initial Trust Deficit: New IP addresses commence with a neutral or unknown reputation, as they lack any prior sending history for Microsoft's systems to assess positively.
- Dynamic Reputation Model: Sender reputation is not static; it is continuously re-evaluated by Microsoft based on evolving sending patterns, volume, recipient complaints, and spam trap interactions.
- Strict Validation Period: Microsoft requires a sustained period of demonstrably clean sending, characterized by minimal spam complaints and robust positive engagement, before elevating an IP's status.
- Complaint Sensitivity: The 'red' status is highly influenced by even a small number of spam complaints, as Microsoft systems prioritize user protection and immediately flag suspicious activity.
- Data-Driven Trust: For a new IP, the 'red' status in SNDS directly reflects the absence of sufficient accumulated positive history needed for Microsoft to grant it a favorable reputation.
Key considerations
- Strict Adherence to Best Practices: Consistently follow email marketing best practices, including list hygiene, opt-in consent, and relevant content, to accelerate positive reputation building with Microsoft.
- Zero-Tolerance for Complaints: During the sensitive warming period, meticulously avoid any spam complaints, as even a minimal number can significantly hinder the IP's progress and prolong its 'red' status.
- Positive Engagement is Crucial: Actively encourage positive recipient engagement, such as opens and clicks, and send only to valid, active users to provide Microsoft's systems with strong positive signals.
- Reputation is Earned: Understand that a positive reputation with Microsoft is earned over time through consistent, clean, and high-quality sending, rather than being an immediate given for new IPs.
- Monitor Beyond SNDS: While SNDS provides insights, also closely monitor actual deliverability metrics, such as inbox placement rates and overall engagement, as a more comprehensive measure of warming success.
Technical article
Documentation from Microsoft Learn explains that new IP addresses begin with a neutral or unknown reputation. It takes time and consistent good sending practices, sending to valid users, and avoiding spam complaints to build a positive reputation, which is why they may appear red or amber in SNDS initially as the system gathers data and assesses the sending patterns.
21 Aug 2021 - Microsoft Learn
Technical article
Documentation from Microsoft explains that sender reputation for IP addresses is not static and is continuously evaluated based on sending patterns, volume, recipient complaints, and spam trap hits. New IPs are initially unknown, and until a sufficient period of clean sending with positive engagement signals is observed, the system will keep the IP in a neutral or negatively-weighted state in SNDS.
3 Mar 2022 - Microsoft Learn
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