Service Incident - October 18, 2025 - All Pods | Email processing delays

Summary

On October 18, 2025, from 12:07 UTC to 13:32 UTC, customers across all production locations experienced delays in receiving inbound emails and a temporary block on outbound emails that lasted approximately 20 minutes. This caused delays in email delivery and degraded spam filtering for all affected customers.

Timeline

October 18, 2025 14:20 UTC | October 18, 2025 07:20 PT

Our engineers have monitored for full recovery and both inbound and outbound email is processing is back to normal. Thank you for your patience and understanding during this incident.

October 18, 2025 13:45 UTC | October 18, 2025 06:45 PT

Beginning at 12:07 UTC Zendesk engineers noticed failures in of one of our email filter services. This caused delays for inbound email processing and outbound mail sending. Our engineers have already taken action and mail has begun processing as of 13:32 UTC. You may notice delays in mail delivery for outbound mail and ticket creation delays for inbound mail during this window.

Root Cause Analysis

This incident was caused by a setup problem combined with an issue at an outside service we rely on. Our spam filtering system depends on updates from this external service to work properly. When the service became unavailable, parts of our system that handle these updates kept failing, which led to the temporary shutdown of important components responsible for filtering emails. As a result, incoming emails were delayed and outgoing emails were briefly blocked.

Resolution

To fix the issue, we turned off the problematic update source, which allowed the email filtering system to return to normal and start processing messages again. Email delivery quickly recovered after this change.

Remediation Items

Adjust the email filtering system to avoid automatic restarts during temporary update issues, preventing interruptions.

Set up a local copy of update data within our network to reduce reliance on external services.

Review and improve how we measure and report delays to better match the actual customer experience.

Improve monitoring to detect update problems sooner and respond more quickly.

FOR MORE INFORMATION

For current system status information about Zendesk and specific impacts to your account, visit our system status page. You can follow this article to be notified when our post-mortem report is published. If you have additional questions about this incident, contact Zendesk customer support.