If filters are not flexible enough, or you find yourself performing the same search again and again, consider a search folder.

A search folder looks like a folder, it acts like a search, and you set it up like a filter. While a conventional folder actually contains messages, a search folder is a view of messages that might be in several different folders. The messages it contains are determined on the fly using a set of criteria that you have chosen when setting up the search folder.

Evolution automatically updates the search folder contents when new messages are received or message are deleted.

The Unmatched search folder is the opposite of other search folders: it displays all messages that do not appear in other search folders.

If you use remote email storage like IMAP, and have created search folders to search through them, the Unmatched search folder also searches the remote folders. If you do not create any search folders that search remote mail stores, the Unmatched search folder does not search in them either.