At 7PM PDT on Tuesday 11/1, the Barracuda Essentials for Email Security service and Cloud Protection Layer experienced elevated bandwidth utilization caused by an unusually high volume of unsolicited inbound DNS responses appearing to be from thousands of globally distributed hosts. This traffic impacted email delivery, message log, and quarantine logs for some customers.
The Barracuda Operations team began deploying defensive measures immediately. These measures restored mail flow through the day as we mitigated the impact of the increased traffic load.
At this time, all systems are fully operational and the mail backlog had cleared as of yesterday afternoon. We are closely monitoring the situation and implementing additional measures to strengthen our infrastructure.
While mail delivery was delayed for some customers, no email was lost, threat scanners were operational, and the administrative user interface was accessible throughout the troubleshooting process. Emails were processed without any data loss and normal delivery resumed as we deployed additional mitigations.