Translations:Kmail/Folder Properties/18/en

The Use custom icons option lets you choose icons that are different from the default ones in the folder list.
With Show column drop down you can set the visible columns in the header pane to Default, Sender, or Receiver. This is useful if you use a folder to save your own sent messages.
In the Message List section you can select and configure an Aggregation and Theme for this folder different from the default configured in KMails settings. For more details see the Message List tab in the Appearance page.