KB03111101 Mailtraq uses 100% CPU after power failure / hard reboot
Mailtraq often uses 100% of available CPU when servicing requests, however you would normally expect this to occur in random bursts matching the pattern of requests.
Mailtraq will also use 100% CPU when it is busy maintaining its databases. During this process it expires messages no longer requires,and compresses its files. This occurs at regular intervals, and at startup. Compression and expiry tasks are shown in the Mailtraq Event Log (Actions | View Event Log)
However, if there is corruption in the database Mailtraq can become confused and use 100% CPU continuously. In this scenario, you may be able to diagnose where the corruption is from messages in the Event Log, otherwise you should restore the Mailtraq database directory from a recent backup.