Yes, CrashPlan allows users to back up files from an external hard drive. When you connect the external hard drive to your computer, CrashPlan recognizes it as a storage device, enabling you to select specific files or entire folders for backup. This functionality is beneficial for protecting important data stored on external drives, which often contain valuable files such as documents, photos, and videos. Users can customize their backup settings to include or exclude specific items on the external drive as per their preferences. Additionally, it is important to ensure that the external drive remains connected during the backup process to avoid any interruptions. For more detailed instructions on backing up from external hard drives, it may be helpful to refer to the resources available on the website.