When you turn off an appliance, the process begins immediately. If you have emails in your message queues, those emails remain in the queues. Before you turn off the appliance, first stop the mail flow. As a precaution, you might also want to flush your inbound, outbound, and delivery message queues.
To turn off an appliance
In the Control Center, click Administration > Hosts > Configuration.
Check the box beside the Scanner that you want to turn off and click Edit.
The Edit Host Configuration page appears, showing the Services tab.
Under MTA Operation, click Do not accept incoming messages.
On the Status > SMTP > Message Queues page, view each of the message queues to see if they are empty.
Click Flush All to flush any queues that contain messages.
You can also click Delete to delete a message or Delete All to delete all messages in a queue.
Repeat the previous step until all queues are empty.
On the Administration > Hosts > Shutdown page, click the Host drop-down list to select the host to turn off.
Before you turn off power to the appliance, be sure the message Power Down appears on a locally connected video console or through a serial connection.