This NewzToolz window is opened by the View Entry button on the Posting Log.
Here you see all of the details of a post except for the body which contains the encoded file – those are too large to save.
The Check if on Server button will log onto the Usenet server, give it the Message-ID, and ask it if it has the post. Normally, you only need to do this when a session is interrupted and you want a quick way to tell if the last post was accepted by the Usenet server.