Earlier versions of Messenger included the concept of an "Address Book" which was a bit like a Group, except that it was difficult to send to all members of the Address Book, and sharing Contacts across Address Books was very messy.
Address Books could be 'Personal' or 'Shared', so they also provided a form of permission, and they were also the only way to import Contacts, so for some users they also acted as 'Lists'. In the latest version of Messenger, if you import contacts, you now import into Groups not 'Address Books'.
Every Contact must have a Security Domain, but we recommend you try to just use the default 'Shared' one unless you are sure you need the complexity that Security Domains bring. If you need to stop some Users from accessing certain Contacts or Groups you can create a 'Security Domain' for those Contacts, and then grant your Users appropriate access permissions.
Unfortunately when removing Address Books we had to create a matching 'Security Domain' for each one because you might have had legitimate security requirements in place, but if this is not the case we strongly recommend you go straight into the 'Security Domains' menu (under 'Contacts'), select those legacy 'Address Books', and use the 'Merge' command to Merge them with the 'Shared' Security Domain. It will tidy things up nicely and reduce confusion among Users.
It will take a while, but it's important to realise that Address Books and Security Domains are NOT the same thing.
- Security Domains are only for controlling access to Contacts.
- Groups are what you use to categorise Contacts.
- Address Books were a strange mix of both.