This policy setting prevents the SharePoint Workspace client from initiating communications to the listed SharePoint Workspace ...

This policy setting prevents the SharePoint Workspace client from initiating communications to the listed SharePoint Workspace Relay Servers.  

If you enable this policy setting, the SharePoint Workspace client will not initiate communication with the listed Groove Relay servers.  You may enter a comma separated list of fully qualified domain names of Groove Relay servers.  Wildcards in the names are supported. The "?" is used for single character substitution and "*" is used for domain part substitution (Examples: relay1.contoso.com, *.contoso.com, relay?.contoso.com).

If you disable or do not configure this policy setting, the SharePoint Workspace client may communicate with any Relay server.