Email Attachment File Path
As far as I know they've got to stay within /sites/default/files/webform/ folder as /sites/default/files is the only folder that should be both writable and publically accessible

If you edit the file component you added to your webform you can then specify a folder within /sites/default/files/webform/ that you'd like them to be stored specifically for that form. Look for the "upload directory" field.