The central server of a Mailborder cluster. This is the only required cluster member type as the Master server forms the Mailborder cluster. The Master server determines the cluster's capabilities through its licensing.
A Mailborder server that expands the cluster's email processing capability. Child servers inherit the Master server's capabilities so if at a later date you wish to upgrade your Master server license to a higher model, you do not have to upgrade the Child server licenses. They will automatically expand in capability to match the Master server.
A virtual Mailborder server contained within the Master server that allows you to grant user level access to the Mailborder cluster. This is a component of the Master server and does not count as a metered device with regards to cluster members.
Based on your selections, you can allow users to view their own email, create rules specific to their email address or aliases, release email, receive reports, and create their own black and white lists. You can also grant Group Administrator privileges to a user that will allow the same actions for all domains in a Group.