A special filtering mode for checking how the rules and the classification algorithm work is called the testing mode. In this mode, the filter classifies all messages marked for training and displays the results in the log. The filter is never actually trained in the testing mode. The log records added in the testing mode have a special prefix.

This mode is useful when you check how the filter recognizes existing messages. You can select one or more messages and mark them as non-spam in the mail client. You can mark spam as well, but if you have the "Move messages marked as junk to the Junk folder" enabled, some messages may suddenly be moved to the Junk folder.

A special icon is displayed on the screen in the testing mode. You can drag it anywhere you like.

You can specify a shortcut for toggling the testing mode in the Shortcuts dialog box.