Hi Michael, Having an SMA in your network would be the solution since you would have a centralized Spam quarantine and you would have a safelist/blacklist option for the centralized quarantine of all appliances hence synchronization between different appliances will be achieved since you will have a signal centralized quarantine.
If you don't have an SMA in your network then you will be using local quarantine on each appliance, hence each will be separated. Also it is also suggested to have backup of your safelist/blacklist. check the following article regarding ESA Safelists/Blocklists Backup Procedure
Regards,
Raed
