The customer's EMarketing synchronisation was taking longer than 15 minutes. There were errors reported in the Emarketing syncengine logs:
FATAL com.sage.scrm.syncengine.core.engine.SyncEngineWatchDog.checkSyncEngineThread Terminating unresponsive integration task...
FATAL com.sage.scrm.syncengine.core.engine.SyncEngineWatchDog.checkSyncEngineThread Killing unresponsive integration task...
These errors were occurring because the sync was taking longer than 15 minutes and the maxsyncthreadinactivityperiod setting in the SPSyncEngine syncengine.properties file was set to 15 minutes.
To resolve this issue we set the maxsyncthreadinactivityperiod setting to 30 and restarted tomcat. The error message did not occur on the next sync.