Resolved after 1 hour 51 minutes, affecting Email sending (SMTP service), on September 29, 2026.
We investigated reports of SMTP connection timeouts and found that some of our incoming mail servers had accumulated stuck mail-handling processes. These processes were consuming excessive processing power, reducing the servers’ capacity to handle other connections and potentially causing slow responses or timeouts. Our investigation identified a possible fault in the handling of an SMTP authentication method. Diagnostic checks showed a process attempting to respond after a connection had closed. We are investigating whether this caused the processes to become stuck; the exact trigger has not yet been confirmed. Actions removed the observed resource buildup, but we are continuing to monitor for recurrence. We are preparing mail-server software updates and assessing whether they address the underlying fault. We are also evaluating a safeguard to detect and clear stuck processes before they affect service.
Affected components
Update timeline
- identified Sep 29, 2026, 08:31 PM UTC
Inbound processing time has decreased due to higher than usual demand. We are adding network capacity to address this.
- resolved Sep 29, 2026, 10:23 PM UTC
This incident has been resolved.
- postmortem Sep 29, 2026, 10:54 PM UTC
We investigated reports of SMTP connection timeouts and found that some of our incoming mail servers had accumulated stuck mail-handling processes. These processes were consuming excessive processing power, reducing the servers’ capacity to handle other connections and potentially causing slow responses or timeouts. Our investigation identified a possible fault in the handling of an SMTP authentication method. Diagnostic checks showed a process attempting to respond after a connection had closed. We are investigating whether this caused the processes to become stuck; the exact trigger has not yet been confirmed. Actions removed the observed resource buildup, but we are continuing to monitor for recurrence. We are preparing mail-server software updates and assessing whether they address the underlying fault. We are also evaluating a safeguard to detect and clear stuck processes before they affect service.
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