You are configuring the device quarantine option.
When the "Notify users when a device is quarantined" option is enabled, users will not actually receive any notification or warning on the machine informing them of the isolation.
Symantec identified an issue with this functionality; the fixed length buffer was not large enough to hold the body of the message.
A fix is planned in 14.3 RU10, where we will dynamically allocate the memory to solve the problem.