This NewzToolz option is located at: Reader window -> Setup Menu -> Settings -> Cross Post
Cross-posting is when somebody posts to more than one group at a time. If you want to post a message to alt.this and alt.that, you don’t have to send the message twice. In the newsgroups header of your post, you can type both newsgroup names. Then the news server will show the post when people look at either group.
Cross-posting is handy for when you participate in two related groups, however spammers will often cross-post their messages to many groups at once. If a message is cross-posted to ten groups, then it is either spam, or the poster is miss-guided. If you see a lot of junk in your favorite groups, try lowering this setting.
You can see how many groups a message was cross-posted to by viewing it in the Read-Post window, and clicking the Headers button. Look at the “Newsgroups” header.
Usenet servers don’t always format posts correctly, so some posts that are over the limit you set here may slip through. (This happens when the Xref header does not contain all of the groups.)