All configuration settings that are set to be synchronized are retrieved from each server and merged together into a single list.

So, for example, if a whitelist on one machine has 10 whitelist entries, while another machine has 20 whitelist entries with 5 of these entries being common to both machines, the end result is a single merged whitelist list with 25 email addresses on both machines. (5 unique from the first machine, 15 unique from the second machine and 5 common from both machines).

This applies to the following features:

• General Settings
• Local Domains
• Access Control
• Perimeter SMTP Servers
• AV Configuration
• Advanced EmailSecurity Configuration
• Templates
• Global Whitelist
• Global Blocklist
• Personal Whitelist and Blocklist
• Auto Whitelist

In the case of content filtering, there is a difference from how whitelists and blocklists are merged.

The rules and settings of Content Filtering engines from every server are gathered and merged into a single list. This applies to the following engines:

This applies to the following Rules and engines:

• Keyword Filtering Rules
• Attachment Filtering Rules
• Advanced Content Filtering Rules
• Decompression Engine

Every update done on one server is immediately applied onto all the other servers. This effectively means that changes are immediately available on all servers.

All slave machines upload all the local reporting/quarantine database data to the machine hosting Quarantine and Reporting. This server requires ample disk space, since it needs to store the quarantine of spam & malware engines, together with reporting data.

If there is no connection to the server (for example, a network outage), slave servers save records locally until the connection is re-established. When a machine is set to send all reporting/quarantine data, all current data in the local databases is transferred. This may take some time, given that a large volume of data may be required to be transferred.