Microsoft has swiftly addressed and rectified a critical issue that affected numerous organizations worldwide. After initially releasing the November 2024 security updates for Exchange Server, Microsoft had to pull them earlier this month due to significant email delivery disruptions experienced by many administrators. However, the tech giant has now re-released the updates, ensuring that businesses can maintain secure and seamless communication without the previous setbacks.
The Initial Setback: Email Delivery Issues
Shortly after the release of the November 2024 security updates for Exchange Server 2016 and Exchange Server 2019, a wave of reports surfaced from administrators. These reports highlighted that emails had ceased to flow within their organizations, particularly impacting those utilizing transport (mail flow) rules or Data Loss Protection (DLP) rules. This disruption was a significant concern, as it impeded everyday business communications and potentially exposed organizations to security risks due to halted email flows.
Recognizing the severity of the issue, Microsoft took immediate action by pulling the problematic updates from both the Download Center and Windows Update. This move was essential to prevent further disruptions and to maintain trust with their enterprise customers.
The Fix: Re-releasing the November 2024 Security Updates
After thorough investigations and swift corrective measures, Microsoft has now re-released the November 2024 security updates, labeled as Nov 2024 SUv2. This updated package specifically addresses and resolves the previously reported mail delivery issues, ensuring that organizations can safely apply the necessary security patches without fear of disrupting their email services.
Key Actions for Administrators
Microsoft has provided clear guidelines for administrators based on their specific scenarios:
Running the Exchange Health Checker
Microsoft strongly advises all administrators to run the Exchange Health Checker script after applying security updates. This tool helps detect common configuration issues that could lead to performance problems and determines if additional steps are necessary to ensure optimal server performance and security.
Enhanced Security Measures: Addressing CVE-2024-49040
The Nov 2024 SUv2 package doesn't just fix the email delivery issues—it also introduces enhanced security features. Notably, it includes more granular control for "Non-RFC compliant P2 FROM header detection". This feature is designed to add warnings to malicious emails that may exploit the high-severity Exchange Server vulnerability CVE-2024-49040. This vulnerability allows attackers to forge legitimate senders, making malicious messages more convincing and effective.
With secure by default settings enabled, CVE-2024-49040 exploitation detection and email warnings are activated on all servers. This proactive approach significantly mitigates the risk of phishing attacks and other malicious activities that rely on spoofed email addresses.
Preventing Future Disruptions: A Strategic Delay
Understanding the critical nature of the upcoming US Thanksgiving holiday, Microsoft strategically delayed the release of Nov 2024 SUv2 via Microsoft/Windows Update until December. This decision was made to prevent servers from automatically installing the update over the holiday period, ensuring that businesses can manage the update process without additional holiday-related complications.
Final Recommendations for Exchange Server Administrators
Stay tuned to WindowsForum.com for more updates on this and other critical IT developments!
Source: BleepingComputer Microsoft re-releases Exchange updates after fixing mail delivery
The Initial Setback: Email Delivery Issues 
Shortly after the release of the November 2024 security updates for Exchange Server 2016 and Exchange Server 2019, a wave of reports surfaced from administrators. These reports highlighted that emails had ceased to flow within their organizations, particularly impacting those utilizing transport (mail flow) rules or Data Loss Protection (DLP) rules. This disruption was a significant concern, as it impeded everyday business communications and potentially exposed organizations to security risks due to halted email flows.Recognizing the severity of the issue, Microsoft took immediate action by pulling the problematic updates from both the Download Center and Windows Update. This move was essential to prevent further disruptions and to maintain trust with their enterprise customers.
The Fix: Re-releasing the November 2024 Security Updates 
After thorough investigations and swift corrective measures, Microsoft has now re-released the November 2024 security updates, labeled as Nov 2024 SUv2. This updated package specifically addresses and resolves the previously reported mail delivery issues, ensuring that organizations can safely apply the necessary security patches without fear of disrupting their email services.Key Actions for Administrators 
Microsoft has provided clear guidelines for administrators based on their specific scenarios:- Manual Installation without Transport or DLP Rules:
- If you installed Nov 2024 SUv1 manually and do not utilize transport or DLP rules, it is recommended to install Nov 2024 SUv2. This update offers more granular control over the
X-MS-Exchange-P2FromRegexMatchheader, enhancing security measures. - Installation via Microsoft/Windows Update without Transport or DLP Rules:
- For those who installed the updates automatically through Microsoft or Windows Update and do not use transport or DLP rules, the system will automatically download and install Nov 2024 SUv2 in December 2024.
- Uninstallation after Installation:
- If you installed Nov 2024 SUv1 (either manually or automatically) and subsequently uninstalled it to rectify the transport rule issues, you should install Nov 2024 SUv2 to ensure your server is secure and operational.
- Servers Not Previously Updated:
- If Nov 2024 SUv1 was never installed, administrators should proceed to install Nov 2024 SUv2 to secure their Exchange Servers against potential vulnerabilities.
Running the Exchange Health Checker 
Microsoft strongly advises all administrators to run the Exchange Health Checker script after applying security updates. This tool helps detect common configuration issues that could lead to performance problems and determines if additional steps are necessary to ensure optimal server performance and security.Enhanced Security Measures: Addressing CVE-2024-49040 
The Nov 2024 SUv2 package doesn't just fix the email delivery issues—it also introduces enhanced security features. Notably, it includes more granular control for "Non-RFC compliant P2 FROM header detection". This feature is designed to add warnings to malicious emails that may exploit the high-severity Exchange Server vulnerability CVE-2024-49040. This vulnerability allows attackers to forge legitimate senders, making malicious messages more convincing and effective.With secure by default settings enabled, CVE-2024-49040 exploitation detection and email warnings are activated on all servers. This proactive approach significantly mitigates the risk of phishing attacks and other malicious activities that rely on spoofed email addresses.
Preventing Future Disruptions: A Strategic Delay 
Understanding the critical nature of the upcoming US Thanksgiving holiday, Microsoft strategically delayed the release of Nov 2024 SUv2 via Microsoft/Windows Update until December. This decision was made to prevent servers from automatically installing the update over the holiday period, ensuring that businesses can manage the update process without additional holiday-related complications.Final Recommendations for Exchange Server Administrators 
- Immediate Action: If you experienced email delivery issues after installing Nov 2024 SUv1, proceed to install Nov 2024 SUv2 as per the guidelines.
- Regular Monitoring: Utilize the Exchange Health Checker regularly to identify and address potential configuration issues promptly.
- Stay Informed: Keep abreast of Microsoft's announcements and updates to ensure your systems remain secure and operational.
- Backup Data: Always ensure that you have recent backups of your Exchange Server data before applying any updates or patches.
Stay tuned to WindowsForum.com for more updates on this and other critical IT developments!
Source: BleepingComputer Microsoft re-releases Exchange updates after fixing mail delivery
