I just purchased this script and am trying to figure out the purpose of the paypal_email data table. I have done a few transactions but have nothing written to it. I also scanned the index.php and functions.php files and found no reference to it.

Help please and thanks!

That was included for an option to create paypal buttons that was eventually taken out since Paypal changes their scheme from time to time. You can delete it if it bothers you. :)