Licensing

Hello, I am trying to find out how licensing works for Symantec Email Protect.  Does each user email address, distribution list, shared mailbox, etc. require a license to be purchased.  I believe we were told at one time that shared mailboxes, such as support@company.com and distribution lists, such as DL-All-Users@company.com would not require that a license be purchased.  We are now being told that any "user" in email protect does require a license.  Thanks!