When you install a Mailbox server running the Transport service, two Receive connectors are created. No additional Receive connectors are needed for typical operation, and in most cases the default Receive connectors don't require a configuration change. These connectors are the following:

• Default <server name>   Accepts connections from Mailbox servers running the Transport service and from Edge servers.
  
  
• Client Proxy <server name>   Accepts connections from front-end servers. Typically, messages are sent to a front-end server over SMTP.
  
  

Each connector is assigned a TransportRole value. You can use it to determine the role the connector is running in. This can be helpful in cases where you are running multiple roles on a single server. In the case of each Receive connector previously mentioned, their TransportRole value is HubTransport.

To view the default Receive connectors and their parameter values, you can use the Get-ReceiveConnector cmdlet.

During installation, three Receive connectors are created on the Front End transport, or Client Access server. The default Front End Receive connector is configured to accept SMTP communications from all IP address ranges. Additionally, there is a Receive connector that can act as an outbound proxy for messages sent to the front-end server from Mailbox servers. Finally, there is a secure Receive connector configured to accept messages encrypted with Transport Layer Security (TLS). These connectors are the following:

• Default FrontEnd <server name>   Accepts connections from SMTP senders over port 25. This is the common messaging entry point into your organization.
  
  
• Outbound Proxy Frontend <server name>   Accepts messages from a Send Connector on a back-end server, with front-end proxy enabled.
  
  
• Client Frontend <server name>   Accepts secure connections, with Transport Layer Security (TLS) applied.
  
  

In a typical installation, no additional Receive connectors are required.

A permission group is a predefined set of permissions that's granted to well-known security principals and assigned to a Receive connector. Security principals include users, computers, and security groups. The use of permission groups simplifies the configuration of permissions on Receive connectors. The PermissionGroups property defines the groups or roles that can submit messages to the Receive connector and the permissions that are assigned to those groups.

Permission groups include Anonymous, ExchangeUsers, ExchangeServers, ExchangeLegacyServers, and Partner.

The type determines the default permission groups that are assigned to the Receive connector and the default authentication mechanisms that are available for session authentication. The following list describes the available types:

1. Client   Typically used to connect to clients not using Microsoft Office Outlook. It can use TLS authentication.
   
   
2. Custom   Typically used in a cross-forest scenario, or in a scenario where your organization receives messages from an SMTP message transfer agent.
   
   
3. Internal   Used for communication between servers running the Transport service, or between Mailbox servers running the Transport service and third-party transfer agents.
   
   
4. Internet   Used to receive SMTP mail from the Internet.
   
   
5. Partner   Use this type when you want to configure secure communication with a partner.
   
   

Each type is appropriate for a specific connection scenario. Select the type that has the default settings most applicable to the configuration that you want. You can modify permissions by using the Add-ADPermission and Remove-ADPermission cmdlets. For more information, see the following topics:

• Add-ADPermission
  
  
• Remove-ADPermission