The most powerful search feature in Postbox is the Advanced Search Tool. It will filter messages based on attributes shared by every email message, and only find messages which meet specific criteria.
Performing an Advanced Search
To start a new search, navigate to Edit > Find > Advanced Search..., or press Shift + Command + K (on Mac) or Shift + Ctrl + K (on Windows).
In a pop-up window, your first choice is where you would like to perform the search, and whether Postbox should look into subfolders when delivering your results. Then, you can set up filters to narrow down the results to be exactly what you want, since Postbox is able to search for specific attributes that are contained inside each message.
Once the results appear (it may take a few moments for a large amount of results), there are many functions that you can perform with messages you select. You can open messages to read them, file them in a specific folder, delete them, or open the folder in which they live.
Additionally, you can convert the Advanced Search into a Smart Folder to instantly perform the same search in the future with just one click in the main window.