Users may be unable to send email externally and may receive DNS-related errors.

Title: Users may be unable to send email externally and may receive DNS-related errors. User impact: Users may be unable to send email externally and may receive DNS-related errors. More info: Users attempting to send email to external recipients may receive DNS-related errors indicating that the destination domain does not exist. Proofpoint is providing updates through its status page: https://proofpoint.my.site.com/community/s/proofpoint-current-incidents. The provider's communication includes a temporary workaround that affected organizations may evaluate while remediation activities continue. Final status: We've completed our investigation and confirmed that the Microsoft-managed Exchange Online infrastructure remained healthy throughout the event. Our findings indicate that the issue was caused by a DNS-related problem within a third-party email service. Since the Microsoft 365 service remains healthy and the issue does not originate within the Microsoft-managed environment, we're closing this Service Health Dashboard communication. Customers should continue to follow the Proofpoint status page for future updates and guidance, including temporary mitigation options provided by the third-party service. Scope of impact: Impact is limited to organizations that route email through the affected third-party email service, Proofpoint. Most reported impact was observed in North America, though reports were also received from additional regions. Start time: Friday, August 14, 2026, at 12:00 PM UTC End time: Friday, August 14, 2026, at 2:35 PM UTC Root cause: A DNS-related issue within a third-party email service caused failures when processing certain externally routed email traffic. This is the final update for this event.

Title: Users may be unable to send email externally and may receive DNS-related errors. User impact: Users may be unable to send email externally and may receive DNS-related errors. More info: Users may receive a DNS error, indicating the domain does not exist, when trying to send emails externally. Proofpoint are providing updates on their status page: https://proofpoint.my.site.com/community/s/proofpoint-current-incidents Some organizations have reported that the issue resolves once removing the third-party from their mail flow configuration. Current status: We've identified that emails routed through a specific third-party email service are experiencing DNS-related issues. The third-party is aware of the issue and are providing updates through their status page: https://proofpoint.my.site.com/community/s/proofpoint-current-incidents We're performing the final validations to confirm that the Microsoft-managed environment remains healthy. Scope of impact: Impact is specific to organizations that use a specific third-party email service (Proofpoint). The majority of reported impact is from users in North America; however, we're aware of additional reports from users in other regions and are continuing to investigate the full scope of impact. Start time: Friday, August 14, 2026, at 12:00 PM UTC Next update by: Friday, August 14, 2026, at 3:00 PM UTC

Title: Some users may experience issues with mail flow in Exchange Online User impact: Users may experience issues with mail flow in Exchange Online. More info: Users may receive a DNS error, indicating the domain does not exist, when trying to send emails externally. Current status: We're continuing to analyze diagnostic data and service telemetry from email processing systems. Additionally, we're reviewing logs from affected email transactions to help isolate the source of impact. We're also aware of reports of similar impact affecting a third-party email delivery service and are investigating whether the events are related. Scope of impact: The majority of reported impact is from users in North America; however, we're aware of additional reports from users in other regions and are continuing to investigate the full scope of impact. Next update by: Friday, August 14, 2026, at 3:00 PM UTC

Title: Some users may experience issues with mail flow in Exchange Online User impact: Users may experience issues with mail flow in Exchange Online. Current status: We're reviewing diagnostic data and monitoring telemetry to isolate the source of the issue. Scope of impact: The impact is being reported by users in the North America region. We're continuing to investigate the full scope of the issue and will update this as we confirm more information. Next update by: Friday, August 14, 2026, at 2:00 PM UTC

Title: Some users may experience issues with mail flow in Exchange Online User impact: Users may experience issues with mail flow in Exchange Online. Current status: We've received reports indicating a potential issue with mail flow in Exchange Online, and checking for impact to your organization. We'll provide an update within 30 minutes.