The call succeeded and has returned the expected value or values.
Remarks
Message store providers implement the IMSLogon::Logoff method to forcibly shut down a message store provider. IMSLogon::Logoff is called:
While MAPI is logging off a client after a call to the IMAPISession::Logoff method.
While MAPI is logging off a message store provider. In this case, IMSLogon::Logoff is called as part of MAPI processing the IUnknown::Release method of the support object that the message store provider creates while it is processing an IMsgStore::StoreLogoff or IUnknown::Release method call on a message store object.