What is Edge subscription and process to enable Edge subscription?

Exchange 2007 Edge Transport server role is always deployed in organization’s DMZ (perimeter) network. Edge Transport server handles all Internet mail flow. It also provides some additional protection and security provided by a series of agents running on the Edge Transport server. These agents protect messages against viruses and spam and apply transport rules to control message flow.

This is an optional process, subscribing an Edge Transport server provide anti-spam features, recipient lookup or safelist, or secure SMTP communications.

Edge Subscription Process

A. Make sure that the Hub Transport servers and the Edge Transport server can resolve the each other FQDNs by using DNS.

B. Run the New-EdgeSubscription cmdlet in the EMS on the Edge Transport server to export the Edge Subscription file.

C. Copy the Edge Subscription file to a Hub Transport server.

D. Run the New-EdgeSubscription cmdlet in the EMS or EMC to import the Edge Subscription file.