Summary

From Thursday, September 24, 2026, at approximately 17:07 (UTC), to Friday, September 25, 2026, at around 09:16 (UTC), some customers experienced intermittent slowness, errors, and delayed mail flow for US instances of Protect and Prevent.

On September 24, an unusually large spike in email traffic placed sustained load on the network services that handle traffic for our US mail processing. Our monitoring alerted us at approximately 17:07 (UTC). Some customers saw slow or intermittent access to Protect and occasional errors when loading pages or advanced options. Access was inconsistent, so some customers could use Protect while others saw errors. Mail processing through US instances slowed, and some messages were delayed or didn't appear in the moderation inbox when expected.

Performance appeared to improve, so we moved our status page notice to Monitoring at 18:39 (UTC). The issue later recurred, and customers reported continued slowness to our support team. At 19:57 (UTC), we moved the notice back to Investigating and expanded it to also include Prevent as the impact became clearer.

Our team monitored the affected systems while the elevated mail volume subsided. As the load on the network services returned to normal, mail processing recovered, and mail queues returned to normal overnight. We confirmed that Protect was loading normally and that test messages were being delivered again, and then continued monitoring. Protect and Prevent returned to normal performance by around 09:16 (UTC) on September 25, 2026.

No data loss occurred as a result of this issue.

Root Cause

This issue was caused by an unusually large spike in email traffic. The increased volume placed a sustained load on the network services that handle traffic for our US mail processing.

Those network services operate within fixed capacity limits, and their capacity couldn't be scaled up during the spike. Because they couldn't keep up with the surge, they slowed down, and some processing failed intermittently. As a result, a large volume of mail was queued in US mail processing, some pages and actions in Protect returned errors, and some messages were delayed or didn't appear in the moderation inbox when expected.

Two factors made the issue harder to manage. First, because access failed intermittently, some checks succeeded while customers continued to see errors, making recovery harder to confirm. Second, our monitoring showed peak load on the network services more clearly than the current load, which made it harder to judge in real time whether the load was still elevated.

Mitigation and Remediation

We found that the network services handling US mail processing had reached their fixed capacity limits during the traffic spike, and their capacity couldn't be increased during the event. Our team monitored the affected systems while the elevated mail volume subsided and network service load returned to normal. Mail processing then recovered, and queued mail was processed.

Because the issue had previously appeared to improve before recurring, we confirmed recovery in several ways before resolving the incident. We confirmed that Protect was loading normally, that test messages were being delivered through US mail processing, and that support requests were progressing normally. We also monitored overnight and received no new reports from customers on US instances.

Customer Impact

Some customers had slow or intermittent access to Protect, and occasionally saw errors when loading pages or advanced options. Mail processing through US instances was delayed for Protect and Prevent. In some cases, messages were delayed or didn't appear in the moderation inbox when expected.

Customers whose mail is encrypted, decrypted, or moderated as it passes through our US mail processing were more likely to be affected. Most Protect customers using the add-in weren't affected by the mail processing delays. The Protect and Prevent consoles remained available, although some console actions were affected by the slower mail processing.

Preventative Measures

To prevent this type of issue in the future, we're improving our monitoring of unusual increases in email volume. We're also improving our monitoring to show the current load on our network services, not only peak values. In addition, we're evaluating ways to scale our network capacity more dynamically during sudden traffic spikes, and assessing longer-term improvements to the network infrastructure that handles US mail processing.

We've also since increased the capacity of US network services in response to a later incident.