QCS may stop processing and fail to mailbox-enable some stub objects. The UI will continue to be responsive, however no new events will be logged to the event viewer, and packets (emails) will no longer be removed from the service mailbox.
This may occur if QCS receives an object from the sync partner that has a bracket in the "mailnickname" attribute. This causes a syntax error an LDAP query used by the QCS function to mailbox enable the object.
This has been reproduced by the development team and a fix is currently being developed. The CR number is: TF121085
This link was sent from development - the "special characters" section shows the characters that need to be "escaped" in an LDAP query.