You can select a file directly from Box and then choose who can view the file, after you share it in the space.
In the message area, click Attachment , and then choose Share from Box.
Select a file on Box and click .
Then, decide who can view the file in the space:
When people don't have access to the file, they see the file name but they can't view the file or see a thumbnail preview.
Make your selection and click Apply.
Then press Enter, to send the link.