Hello Thomas,
User level approved and blocked senders list already exists within the Symantec Quarantine system. For more information, you can review our guide linked in the article below.
https://support.symantec.com/en_US/article.DOC9389.html
The information begins on page 66. If you need additional assistance on how to enable these lists for users, see below.
Giving users control of their lists
For further assistance, please open a case with our support team.
Regards,
Ben Beaulieu
Sr Technical Support Engineer