When configuring a Communications Preferences Form in BBIS, you are required to include a Global Opt Out element to comply with such laws as the United State's CAN-SPAM act.  The Global Opt Out element applies to ALL sites in a BBIS multi-site implementation.  This creates problems when implementing multi-site, as the opt-out should only be global in terms of the site form which the opt-out originated.  (i.e., if I globally opt out of a message sent from Site A, I should not be blocked from receiving email from a completely different Site B unless I have also globally opted out of email from that site)