This is a cross post from a specific thread within this forum. I realized that it may be helpful to others as well:

If you want to upload a Notebook to the forums, archive the file first before sending it (Control-click the Notebook in the Finder and choose “Compress” from the menu that appears). This creates a .zip format file.

This prevents issues with browsers and web servers that don’t understand that a Notebook file is actually a special folder recognized by the Finder as a single file. They get confused and think it’s a folder. Usually you cannot upload a folder via a web interface.

Hope this helps reduce some work for those posting Notebooks!