Does below command return something?
# ldapsearch -x -D 'cn=vmail,dc=fracassetti,dc=lan' -b 'o=domains,dc=fracassetti,dc=lan' (&(objectclass=mailUser)(accountStatus=active)(enabledService=domainadmin)(domainGlobalAdmin=yes))NOTE: It will prompt to input password of cn=vmail,dc=fracassetti,dc=lan.