dovecot-ldap.conf:
hosts = localhost
dn = cn=dovecot,o=autotechnik,c=cz
dnpass = tocedov
ldap_version = 3
base = ou=people,o=autotechnik,c=cz
deref = never
scope = subtree
user_attrs = uid,homeDirectory,,uid,uidNumber,gidNumber
user_filter = (&(objectClass=posixAccount)(uid=%u))
pass_attrs = uid,userPassword
pass_filter = (&(objectClass=posixAccount)(uid=%u))


dovecot.conf:
auth_userdb = ldap /etc/dovecot-ldap.conf
auth_passdb = ldap /etc/dovecot-ldap.conf