For multi-user accounts, each user has their own contact list, and can see the shared contact lists with all members of the account.
On some devices, syncing with these contact lists just works, and on others it needs a CardDAV entry for each contact list you want to use. (One for your personal address book, and another for the shared address book.)
- The official Fastmail app: just works.
- Android: just works. You connect your CardDAV account and the system lets you select which contact list to sync.
- iPhone/iPad: just works. You connect your CardDAV account and the system automatically syncs all contact lists. You can select which ones to show by using the Groups functionality.
- BlackBerry: Add multiple CardDAV entries, one for your personal contact list and one for the shared contact list.
- Mac Mail: unfortunately does not support multiple contact lists. Automatic profile configuration will show your personal contacts by default. For users in a multi-user account, you can set up shared contacts instead of personal contacts by setting up your account in Contacts manually.
- Thunderbird: Add multiple CardDAV entries, one for your personal contact list and one for the shared contact list.
- Windows emClient: Add multiple CardDAV entries, one for your personal contact list and one for the shared contact list.
You can find details on specific URLs for personal and shared contacts on the server names page.