Public URLs (files) from the Webtools File Manager are no longer allowed within Email+. Files should be uploaded into Email+ on the Files tab. Why? Let's say you send an email that references several images or files from the File Manager. A few days later you delete something within the File Manager that you were referencing in the email. Now the email archive and every email that was sent out has a broken link or image. The proper way to deal with this is to upload your files directly into an email. This way they won't accidentally get deleted and archives are preserved as intended.
If you have any questions please contact Web Services via our Contact Us link at the top of the Toolbox.