Why is Microsoft suddenly making negative changes to sender reputation?

Summary

Microsoft's sudden negative changes to sender reputation can be attributed to multiple factors. These include adjustments to Microsoft's SmartScreen filter, increased scrutiny of sender behavior, and challenges associated with new IP addresses lacking a sending history. Additional causes involve compromised accounts sending spam, inadequate or missing email authentication (SPF, DKIM, DMARC), suspected changes to Microsoft's spam filtering algorithms, spam content, low sender scores, or sudden spikes in email volume. Furthermore, factors such as inconsistent IP reputation, blacklisting (e.g., by Spamhaus), user complaints, and incorrect configuration of SPF records contribute to reputation issues. Monitoring sender reputation, adapting to filtering algorithm changes, and maintaining clean sending practices are essential for managing and mitigating these negative impacts. Microsoft appears to be less likely to offer mitigation for senders with questionable practices. Maintaining a consistent IP address reputation is key to email deliverability.

Key findings

  • SmartScreen Filter Changes: Updates to Microsoft's SmartScreen filter criteria or stricter enforcement can cause sudden reputation shifts.
  • New IP Reputation Issues: New IP addresses without a sending history are vulnerable to deliverability problems, leading to negative reputation.
  • Compromised Accounts and Spam: Compromised accounts sending spam can quickly erode sender trust and damage reputation.
  • Authentication Deficiencies: Missing or improperly configured SPF, DKIM, and DMARC records negatively impact sender reputation.
  • Algorithm and Filtering Adjustments: Changes to Microsoft's spam filtering algorithms can tighten spam detection rules and affect deliverability.
  • Content, Volume, and Sender Score Problems: Spam content, low sender scores, and sudden email volume spikes can trigger blocks by Microsoft's Junk Mail Filter.
  • Blacklisting Impact: Being blacklisted, especially by entities like Spamhaus, severely damages sender reputation and deliverability.
  • Lack of Mitigation: Microsoft is less likely to offer mitigation for senders who aren't cleaning up sending practices.

Key considerations

  • Proactive Reputation Monitoring: Actively monitor sender reputation using tools and track IP addresses to detect drops or blacklistings promptly.
  • Strategic IP Warming: If using a new IP address, implement a gradual IP warming strategy to build a positive sending history.
  • Robust Authentication Implementation: Ensure that SPF, DKIM, and DMARC records are correctly configured and up-to-date to authenticate email sending.
  • Enhanced Account Security Measures: Implement strong security measures to prevent account compromises that can lead to spam sending.
  • High-Quality Content Creation: Review email content to avoid spam triggers and maintain a high sender score.
  • Controlled Email Volume: Avoid sudden spikes in email volume, especially when starting with a new IP or domain.
  • Adaptability to Algorithm Changes: Continuously monitor trends, adapt email sending strategies, and stay informed about filtering algorithm updates to maintain good deliverability.
  • Clean Sending Practices: Ensure email sending practices are clean and compliant to avoid issues with Microsoft and other ISPs.

What email marketers say
11Marketer opinions

Microsoft's sudden negative changes to sender reputation can stem from various factors. These include changes in Microsoft's SmartScreen filter criteria, increased scrutiny of sender behavior, and the impact of sending from new IP addresses without proper warming. Other causes are compromised accounts sending spam, missing or improper email authentication (SPF, DKIM, DMARC), suspected changes to Microsoft's spam filtering algorithms, and issues with spam content, low sender scores, or sudden spikes in email volume. Several sources also recommend proactive monitoring of sender reputation through tools and careful deliverability tracking.

Key opinions

  • SmartScreen Changes: Microsoft's SmartScreen filter algorithm updates or stricter enforcement can lead to sudden reputation changes.
  • New IP Issues: New IP addresses without a sending history are prone to deliverability challenges, impacting reputation negatively.
  • Compromised Accounts: Compromised accounts sending spam can swiftly decrease sender trust and reputation.
  • Authentication Problems: Missing or incorrectly configured SPF, DKIM, and DMARC records negatively affect sender reputation.
  • Algorithm Updates: Microsoft's spam filtering algorithms may change, tightening spam detection rules.
  • Content & Volume: Spam content, low sender scores, and sudden email volume spikes can trigger blocks from Microsoft's Junk Mail Filter.

Key considerations

  • Monitor Reputation: Actively monitor sender reputation using tools and track IP addresses to detect drops or blacklistings promptly.
  • IP Warming: If using a new IP address, implement a gradual IP warming strategy to build a positive sending history.
  • Authentication: Ensure that SPF, DKIM, and DMARC records are correctly configured and up-to-date to authenticate email sending.
  • Account Security: Implement strong security measures to prevent account compromises that can lead to spam sending.
  • Content Quality: Review email content to avoid spam triggers and maintain a high sender score.
  • Volume Control: Avoid sudden spikes in email volume, especially when starting with a new IP or domain.
Marketer view

Marketer from Email Geeks shares their experience that Microsoft is making sudden, negative changes to reputation for some clients, but their support seems to be better at fixing issues for deserving clients.

September 2022 - Email Geeks
Marketer view

Email marketer from SocketLabs answers Microsofts Junk Mail Filter may be blocking mail due to Spam Content within the emails, Low sender Scores and Sudden Spikes in volume.

December 2023 - SocketLabs
Marketer view

Email marketer from Email Marketing Forum suspects changes to Microsoft's email filtering algorithms are the reason behind sudden deliverability issues. The forum poster suggest Microsoft could be tightening its spam detection rules.

March 2023 - Email Marketing Forum
Marketer view

Email marketer from Gmass Blog explains that improper or missing email authentication records (SPF, DKIM, DMARC) can negatively impact sender reputation, as Microsoft may view unauthenticated emails as suspicious.

September 2024 - Gmass Blog
Marketer view

Email marketer from SparkPost Blog explains that Microsoft uses its SmartScreen filter to evaluate incoming email, and sudden reputation changes could be due to changes in the filter's criteria or increased scrutiny of sender behavior.

October 2023 - SparkPost Blog
Marketer view

Marketer from Email Geeks notes they've recently started seeing delays and blocks from Microsoft that weren't happening before.

August 2022 - Email Geeks
Marketer view

Email marketer from Reddit mentions that sudden reputation dips can be caused by compromised accounts sending spam, leading to a rapid decline in sender trust with Microsoft.

May 2021 - Reddit
Marketer view

Email marketer from Talos Intelligence shares the importance of monitoring deliverability and tracking IP addresses. It also details it may be due to sudden blacklists.

March 2025 - Talos Intelligence
Marketer view

Marketer from Email Geeks confirms experiencing rolling issues for several weeks.

February 2023 - Email Geeks
Marketer view

Email marketer from Mailjet Blog shares that new IP addresses often face deliverability challenges, including negative reputation, because they haven't built a sending history. Gradual IP warming can mitigate this, but sudden shifts in sending volume can negatively impact reputation.

March 2024 - Mailjet Blog
Marketer view

Email marketer from Sender Score recommends using tools like Sender Score to actively monitor reputation and identify any sudden drops that could indicate problems with sending practices.

August 2024 - Sender Score

What the experts say
3Expert opinions

Microsoft's stricter stance on sender reputation means they are less likely to offer mitigation for senders with questionable practices. Maintaining a consistent and positive IP reputation is crucial, as being added to a blocklist can hinder deliverability. Sudden shifts in inbox placement can occur due to algorithm changes and emerging blacklists, emphasizing the need for constant monitoring and adaptation to new trends.

Key opinions

  • Stricter Mitigation: Microsoft is less forgiving towards senders with questionable practices, limiting mitigation efforts.
  • IP Reputation: Consistent IP address reputation is key, with blacklisting impacting deliverability.
  • Algorithm & Blacklists: Inbox placement changes due to filtering algorithm updates and blacklisting are common.

Key considerations

  • Clean Practices: Ensure email sending practices are clean and compliant to avoid issues with Microsoft.
  • Reputation Monitoring: Monitor IP address reputation consistently to identify and address any blacklisting or negative trends.
  • Adaptability: Continuously monitor trends, adapt email sending strategies, and stay informed about algorithm changes and blacklists to maintain good deliverability.
Expert view

Expert from Spam Resource explains that maintaining a consistent IP address reputation is key to email deliverability. If your IP address gets added to a block list, then your deliverability may be hindered.

May 2021 - Spam Resource
Expert view

Expert from Email Geeks explains that if your sending practices aren't clean, Microsoft seems less likely to offer mitigation.

March 2022 - Email Geeks
Expert view

Expert from Word to the Wise explains that fluctuations in inbox placement can happen suddenly due to many factors, including changes in filtering algorithms and emerging blacklists. Monitoring trends and adapting to the signals should be prioritised.

March 2023 - Word to the Wise

What the documentation says
5Technical articles

Microsoft's sender reputation is influenced by email volume, complaint rates, and authentication practices. Sudden negative changes often result from increased spam complaints or authentication failures. Spam traps, user complaints, and blacklisting, particularly by Spamhaus, severely harm reputation. Proper SPF record configuration prevents spoofing, and adherence to DMARC policies is crucial for sender credibility. Overall, robust authentication via DMARC, SPF, and DKIM prevents spoofing and increases sender domain reputation.

Key findings

  • Reputation Factors: Email volume, complaint rates, and authentication methods heavily influence sender reputation.
  • Complaint/Auth Impact: Spikes in spam complaints or authentication failures lead to sudden negative changes.
  • Blacklisting Effect: Blacklisting by Spamhaus and other entities severely damages sender reputation.
  • SPF Importance: Incorrect SPF configuration leads to authentication failures and damaged reputation.
  • DMARC Adherence: Failure to adhere to DMARC policies can affect credibility.
  • Authentication Enhancement: Utilizing authentication methods DMARC, SPF, and DKIM prevents spoofing and enhances sender reputation.

Key considerations

  • Monitor Metrics: Monitor email volume, complaint rates, and authentication success to identify and address issues promptly.
  • Avoid Spam Traps: Implement measures to avoid sending to spam traps, which can lead to blacklisting.
  • Proper Authentication: Correctly configure SPF, DKIM, and DMARC records to ensure proper authentication and prevent spoofing.
  • DMARC Compliance: Strictly adhere to DMARC policies and monitor DMARC reports to identify and correct authentication issues.
  • User Complaints: Reduce user complaints by creating content users value and segmenting lists for appropriate messaging.
Technical article

Documentation from Microsoft Docs explains that sender reputation is based on factors like email volume, complaint rates, and authentication practices. Sudden negative changes may result from a spike in spam complaints or authentication failures.

June 2024 - Microsoft Docs
Technical article

Documentation from Google Admin explains authenticating mail helps prevent spammers from spoofing your organization. By setting up DMARC, SPF, and DKIM will enhance your sender domain reputation.

August 2024 - Google Admin
Technical article

Documentation from Dmarc.org explains that DMARC policies need to be strictly followed, and any discrepancies can affect a sender's credibility. It also documents what can cause failures.

March 2024 - Dmarc.org
Technical article

Documentation from RFC-Editor documents what SPF records are, explaining that SPF records help prevent email spoofing. Incorrect configuration can cause failed authentication, damaging reputation.

August 2022 - RFC-Editor
Technical article

Documentation from Spamhaus explains that factors like spam traps, user complaints, and blacklisting can significantly impact a sender's reputation with ISPs like Microsoft. Being listed on a Spamhaus blacklist will cause reputation harm.

March 2023 - Spamhaus