You should not paste the results of a test message back into the editor This will break the click-track statistics, and overload the server.

This error may appear when you edit a campaign. It is caused by the campaign content containing links that are click-track links.

These links will look like

http://yoursite/lists/lt.php?id=XXX

If links like this are found in your content, it means you copied the results of a test campaign, or other campaign back into the phpList editor. This should be avoided.

Remove the links from your content and replace them with the original URL.