The Setting Up Postbox section describes how to set up Postbox to filter your mail using SpamSieve. Versions 2.x through 5.x of Postbox are supported.
To test that the setup works:
The setup is correct if there’s a log entry (near the bottom) that says Predicted: Good or Predicted: Spam and shows the subject for the new message.
If you don’t see the expected log entries for new messages, please contact technical support and explain what happened when you followed these instructions.