Summary
Files cannot be quarantined again by content keyword filtering after you restore them from the quarantine folder in PortalProtect 2.1.
Details
The issue occurs because the restored files are not scanned immediately when you download the files. PortalProtect's real-time scan service depends on Windows SharePoint Virus Scan Engine API. When you restore a quarantined file, the file is trusted and SharePoint Service keeps the virus stamp cache.
When the cache expires after 20 minutes, the file will be quarantined again by PortalProtect real-time scan.