After you have configured the on-demand scan and selected which mailboxes to scan, you can run the on-demand scan immediately.To run the on-demand scan immediately
In the Forefront Protection 2010 for Exchange Server Administrator Console's Tasks view, in the tree, expand Task Library, and then click Mailbox On-Demand.
In the Task Library - Mailbox On-Demand pane, in the Actions section, click Start On-Demand Scan. This sets the start time to the current time, thus starting the scan.
Note: To stop an on-demand scan that is running, in the Actions section, click Stop On-Demand Scan. To suspend a running on-demand scan, in the Actions section, click Suspend On-Demand Scan. To resume a suspended on-demand scan, in the Actions section, click Resume On-Demand Scan. Clicking Resume On-Demand Scan starts a suspended scan from where it left off; however, if you click Start On-Demand Scan when a scan has been suspended, the scan starts from the beginning again. You do not need to click Save to start or stop an on-demand scan.
After running the on-demand scan, you can use the Forefront Management Shell to check its status.To check scan status
Click Start, point to All Programs, point to Microsoft Forefront Server Protection, and then click Forefront Management Shell.
Enter the following Windows PowerShell command:
The status can be ACTIVE, STOPPED, or SUSPENDED. A status of ACTIVE indicates that the scan is still running, STOPPED indicates that it has completed, and SUSPENDED indicates that it was paused.