Virtual Folders
The Virtual Folders feature can be accessed via the toolbar button and Tools menu of the program's main window. The button by that name on the Address Book window will also give you a Virtual Folder of messages to and from the selected address.
When accessed using the toolbar button or the Tools menu, this function results in the Virtual Folder Specification dialog. This lets you select which type of search you want to perform, and specify which folders you want included in the search. By default, all of your folders are selected except TRASH and Print Queue.
If you select one of the bottom four radio buttons, a dialog will follow which will let you specify the list of strings for which you want to search.
The program will very quickly search the index files for every folder in the current account, and open the Virtual Folder results window to show you all of the messages which match your search criteria. The one exception is the last radio button, body contains, which makes the program search each entire message instead of only the index files, so it takes much longer.
The Virtual Folder results window is very much like the program's main window. The message list panel has one additional column at the right end, which tells you the name of the folder where each of the found messages actually resides. If you add a sticky note to a message in this window, or delete it, or move it, you'll be performing those actions upon the file in that folder, not just the one in the Virtual Folder results window, because they're actually one and the same. The messages in this window are not copies of the originals, but pointers to the originals.