Here are the settings one customer used to configure our LDAP sync tool ("Tools->LDAP user sync") to work with Kerio Connect 8:
LDAP SERVER
Directory Type: Other
Hostname: fqdn.domain.com (IP address only works for non-SSL connections)
Port: <Blank>
Use SSL Connection: <Checked>
AUTHENTICATION INFO
Username: <Any Kerio Account>
Password: <Kerio Account Password>
SEARCH PARAMETERS
Base DN: fn=ContactRoot
Email Attributes: mail,uid,otherMailbox,rfc822Mailbox,apple-generateduid
Filter: (objectClass=inetOrgPerson)
AUTOMATIC SYNCHRONIZATION
Frequency of Auto-sync: <Whatever works best for your organization>
Email Address: postmaster@domain.com