I saw one error Id in the event 9335
OABGen encountered error 80004005 while cleaning the offline address list public folders under /o=domaine/cn=addrlists/cn=oabs/cn=msExchOAB15219439. Please make sure the public folder database is mounted and replicas exist of the offline address list folders. No offline address lists have been generated. Please check the event log for more information.
– default offline address book