In simpler words Edge Transport role is deployed in perimeter network of the organization. It handles all internet mail flow which provides SMTP relay and smart host services for the exchange.
It has additional layers of security by a series of agent that is run on the server and acts as they processed by the message transport component.
The Edge transport server doesn’t have access to the active directory. To perform recipient look ups tasks, the edge transport server uses active directory light weight directory services with the help of edge sync subscription.
The subscription is a one-way replication of recipient and configuration information from Active Directory to the AD LDS instance on an Edge Transport server
You can install more than one edge transport server in the perimeter network to provide redundancy and fail over capabilities for your inbound message flow.
Below are some message processing scenarios that you can manage on the Edge Transport server role
- Internet Mail Flow
- Anti-Spam and Antivirus Protection
- Edge Transport Rules
- Address Rewriting
Please find the attached document to how to install Edge Transport role, create a edge subscription in Edge Transport and import the same in Hub Transport Server. Edge