Q: I would like to have a list of the e-mail addresses of the students in my course but can't seem to extract them from the Blackboard site. Is there a way to put the addresses into a text file?

A: Yes.

From your Blackboard site's control panel:

1. Go to User Management > List/Modify Users
2. Place your cursor directly to the right of the first letter of the first name on the list, click and hold.
3. Drag down to highlight the rest of the page
4. Hit Ctrl & C or Apple & C on your keyboard to copy
5. Open a blank text file page (such as Notebook)
6. Click in the top left corner of the blank text file page, and hit Ctrl & V or Apple & V on your keyboard to paste
7. Save text file page to desktop and close
8. Open Excel and from the File menu, select Open
9. Find the text file page you just saved in the dialog box that opens, select it, and click the Open button (you may have to change "Files of type" to "All Files" or "Text Files" to find it)
10. In the next dialog box that opens, select Delimited and click Next
11. Select "Space" as your delimiter and click Next
12. Click Finish
13. Double click the top of the column in Excel that has the e-mail addresses
14. Hit Ctrl & C or Apple & C on your keyboard to copy
15. Now you can paste the list into a text file or into your e-mail. You can also paste them directly into a To line of an e-mail composition and hit enter. In most clients, this will put them each on a separate line. You could also paste them into the address book. 

http://www.princeton.edu/bb/bbfaq/Questions/email.htm