Kerio MailServer supports Apple Address Book, the standard directory of Mac OS X. This support includes the option of searching for contacts in the Kerio MailServer's LDAP database and, since Mac OS X 10.3, also of bi-directional synchronization of contacts with Kerio MailServer's user accounts .

Kerio MailServer supports Apple Address Book for the following versions:

Setting options are different for these versions — therefore, they will be focused in separate sections: