Solution : https://service.sap.com/sap/support/notes/1111968 (SAP Service marketplace login required)
Key words : 
relevant support package, adapter status reason, 999 parallel queues xbtb$, 999 parallel queues, idoc adapter, prefix xbtb$, report sxms_refresh_adapter_status, short period, terms acknowledgment, exchange infrastructure
Related Notes : 
       
| 1137791 | NW04s Support Package Stack 15 | 
| 1118297 | XI runtime: QRFC processing of messages |