Finding things in Finder · Opening and using moved files
Can I attach a moved file to an email or upload it from its usual folder?
Short answer: Yes. Choosing the file from its usual folder in an Open or Attach window gives the app the real file from your external drive, as long as it's connected. To copy the actual file elsewhere, use Show Original first.
Yes. When you pick the file from its usual folder in an app's Open or Attach window, macOS follows the shortcut and hands the app the real file from your external drive. The drive must be connected.
If you copy the shortcut itself somewhere — onto a USB stick, or to another Mac — you may only copy the link, not the file. To give someone the actual file, copy it from the drive: select the shortcut, choose File → Show Original, and copy the item Finder shows you.