I had this working with ZCS 5.0.7, but I can't seem to get it working in 6.0.10.
Here's what I've tried, in Thunderbird:
base dn: ou=people,dc=_domainname_,dc=com
search filter: (mail=*)
Login method: simple
When I search, it appears to succeed but returns 0 results. If I alter the base dn, Thunderbird reports that the replication failed.
Any ideas on how to debug / fix this?