When you message a student within Blackboard from a course that has not yet opened up for the semester, students will not be able to open any attached files within the message. If you choose to send the message to their RIC email, they will not be able to open the attached file. The best way for students to access attachments sent from a closed course is by attaching that file to your OneDrive account via a link.
Emails to students will look like the image below, but when they click on the attachment or the "view message" box, it will prompt them to log into their Blackboard course. Since the course will be closed, they will not be able to access the attachment.
The best way for students to access an attachment sent in a closed Blackboard course is by linking that attachment from your OneDrive account. Directions on how to do that can be found below: