Filtering assets in reports is not supported in Satellite Mode (the ‘open in a new window’ icon on the right of the asset detail page).
Go to Analytics (or Marketing Activities) area.
Select your email performance report.
Click the Setup tab and drag over a filter.
Choose the folders and specific smart campaigns to include in your report.
If you select a folder, your report will include everything that folder contains at the time the report runs.
You’re done! Click the Report tab to see your filtered report.