Zoho Mail suggests filters based on your email addresses, aliases, and groups. You can edit the recommendations and add them to your filters section. Learn more.
The 'Run Through Filter' option processes messages that were received before the creation of the filter. The run through can be scheduled for a specific folder from the Filter Settings menu. Learn More.
Some messages might fall under more than one filter category. While being processed by multiple filters, certain filter actions might be repeated more than once. Some actions take place even when repeated. But actions such as 'Move to Folder', ...
Selecting a parent folder for Run Through Filter will affect that folder alone. Each subfolder should be selected separately to process messages in that folder.