Accepted domains are SMTP namespaces for which an Exchange organization sends and receives e-mail. An Exchange organization is considered authoritative for a specific accepted domain if it handles all mail delivery for recipients in that domain. Typically, the accepted domains that you use in a new installation are all authoritative. However, there are other types of accepted domains, which you may want to use depending on your needs.

To learn more about accepted domains, see Understanding Accepted Domains.

Accepted Domains in the Exchange Organization

By default, one accepted domain exists and is configured as authoritative for the Exchange organization during installation. The default authoritative domain is the fully qualified domain name (FQDN) of your Active Directory forest root domain. In many organizations, the internal domain name differs from the external domain name.

For example, your internal domain name may be contoso.local, and your external domain name may be contoso.com. The public Domain Name System (DNS) MX resource record for your organization will reference contoso.com. To send and receive e-mail across the Internet, you must configure contoso.com as an accepted domain. Also, if your Exchange organization is handling mail for more than one domain, you must specify these additional domains as accepted domains.

Accepted domains need to be configured only once for the Exchange organization after you deploy your first Hub Transport server.

For step-by-step instructions about creating accepted domains, see Create an Accepted Domain.

Note:
If you configure additional accepted domains for your organization, you need to update your e-mail address policies to assign these domain names to your recipients. To learn more about e-mail address policies, see Understanding E-Mail Address Policies.

Accepted Domains on Edge Transport Servers

After you install your first Hub Transport server, you must create additional connectors to begin sending and receiving messages from the Internet. The following connectors are created when you install your first Hub Transport server:

• Intra-organization Send connector   This implicit Send connector isn't visible in the management tools and is computed based on your Active Directory site topology. This Send connector enables your Hub Transport servers to communicate with each other. For more information about internal message routing, see Understanding Message Routing.
  
  
• Receive connector configured to accept messages from all remote IP addresses through port 25   This connector typically accepts connections from all IP address ranges. The usage type for this connector is Internal. This connector only accepts mail from other Exchange servers that are part of the same Exchange organization. By default, this connector doesn't accept anonymous submissions.
  
  
• Receive connector configured to receive messages from all remote IP addresses through port 587   This connector is used to accept SMTP connections from POP3 or IMAP4 clients. This connector typically accepts connections from all IP address ranges. The usage type for this connector is Internal.
  
  

When you install an Edge Transport server, only the following connector is created during setup:

• Receive connector configured to receive messages from all remote IP addresses through port 25   This connector is used for both incoming Internet e-mail and incoming e-mail from the Hub Transport servers. The permissions on the connector are automatically determined by how sessions are authenticated.
  
  

To learn more about connectors, see Understanding Send Connectors and Understanding Receive Connectors.

After a default installation:

• Your Hub Transport servers can communicate with each other.
  
  
• Your Hub Transport servers can receive message submissions from your Mailbox servers and non-MAPI clients (such as POP3 or IMAP4).
  
  
• Your Edge Transport server can receive messages from the Internet and your Hub Transport servers.
  
  

To complete deployment, you need to:

• Configure your Hub Transport servers to forward Internet messages to your Edge Transport servers.
  
  
• Configure your Edge Transport servers to send Internet messages to the Internet.
  
  
• Configure your Edge Transport servers to forward inbound messages to your Hub Transport servers.
  
  

You have two options to accomplish the additional tasks. For best results, we recommend that you subscribe your Edge Transport servers to your organization. The options are described in the following topics:

• Configure Internet Mail Flow Through a Subscribed Edge Transport Server
  
  
• Configure Mail Flow Between an Edge Transport Server and Hub Transport Servers Without Using EdgeSync
  
  

If you don't use Edge Transport servers in your organization, you have two options for configuring Internet mail flow. Keep in mind that configuring Internet mail flow directly through your Hub Transport servers isn't recommended. The options are described in the following topics:

• Configure Internet Mail Flow Through Exchange Hosted Services or an External SMTP Gateway
  
  
• Configure Internet Mail Flow Directly Through a Hub Transport Server