Pre-requisite feature/role

Active Directory Lightweight Directory Service.

PS C:\> Install-WindowsFeature ADLDS

Success Restart Needed Exit Code      Feature Result
------- -------------- ---------      --------------
True    No             Success        {Active Directory Lightweight Directory Se...
WARNING: To create a new AD LDS instance on server, log on to the destination server and then run the Active Directory
Lightweight Directory Services Setup Wizard. For more information, see http://go.microsoft.com/fwlink/?LinkId=224859.

Install

# INSTALLING EXCHANGE SERVER 2013 EDGE TRANSPORT ROLE
setup /m:install /r:et /IAcceptExchangeServerLicenseTerms

Firewall

25/TCP - SMTP (Inbound from and outbound to ALL)

50389/TCP - LDAP(Local only)
This port is used to make a local connection to AD LDS.

50636/TCP - Secure LDAP(Inbound from the internal network)
This port is required for EdgeSync synchronization.
 

EdgeSync

The recommended deployment process is to create an Edge Subscription to subscribe the Edge Transport server to the Exchange organization. When you create an Edge Subscription, recipient and configuration data is replicated from Active Directory to AD LDS. You subscribe an Edge Transport server to an Active Directory site. Then the Microsoft Exchange EdgeSync service that is running on the Mailbox servers in that site periodically updates AD LDS by synchronizing data from Active Directory. The Edge Subscription process automatically provisions the Send connectors that are required to enable mail flow from the Exchange organization to the Internet through an Edge Transport server. If you're using the recipient lookup or safelist aggregation features on the Edge Transport server, you must subscribe the Edge Transport server to the organization.

Note: Edge doesn’t need to be Domain joined machine although you can also use a domain Joined Machine for installing Edge Transport Role. However, workgroup machine still need to resolve Mailbox Server Name and mailbox Server must be able to resolve Edge Server so FQDN is required.