Understanding Remote Domains

Applies to: Exchange Server 2010 SP3, Exchange Server 2010 SP2

You can create remote domain entries to define the settings for message transfer between the Microsoft Exchange Server 2010 organization and domains outside your Active Directory forest. When you create a remote domain entry, you control the types of messages that are sent to that domain. You can also apply message format policies and acceptable character sets for messages that are sent from users in your organization to the remote domain. The settings for remote domains are global configuration settings for the Exchange organization.

The remote domain settings are applied to messages during categorization. When recipient resolution occurs, the recipient domain is matched against the configured remote domains. If a remote domain configuration blocks a specific message type from being sent to recipients in that domain, the message is deleted. If you specify a particular message format for the remote domain, the message headers and content are modified. Information about the remote domain configuration is stored in Active Directory. The settings apply to all messages that are processed by the Exchange organization.

By default, there's a single remote domain entry. The domain address space is configured as an asterisk (*). This represents all domains. If you don't create additional remote domain entries, all messages that are sent to all recipients in all remote domains have the same settings applied to them.

When you configure remote domains, you can prevent certain types of messages from being sent to that domain. These message types include out-of-office messages, auto-reply messages, non-delivery reports (NDRs), and meeting forward notifications. If you have a multiple forest environment, you may want to allow the sending of those types of messages to those domains. However, if you have identified a domain from which spam originates, you may want to block sending of those types of messages to those remote domains.

Message Format

You can specify the message format and the character set to use for e-mail messages that are sent to remote domains. These settings can be useful to make sure that e-mail sent by senders in your domain to the remote domain is compatible with the receiving e-mail system. For example, if you know that the remote domain's messaging system is Exchange, you can specify to always use Exchange rich text format (RTF). For more information, see Understanding Content Conversion.

Automatic Replies Settings

Automatic replies, formerly known as out-of-office replies, have changed substantially starting with Exchange Server 2007. In Exchange 2010 and Exchange 2007, users can specify different automatic replies for internal and external recipients. Furthermore, the types of automatic replies available in your organization also depend on the Microsoft Outlook version in use.

In Exchange 2010, there are three types of automatic replies:

• External   Supported by Exchange 2010 and Exchange 2007. Can only be set by Outlook 2010 or Office Outlook 2007, or using Microsoft Office Outlook Web App.

• Internal   Supported by Exchange 2010 and Exchange 2007. Can only be set by Outlook 2010 or Outlook 2007, or using Outlook Web App.

• Legacy   Supported by Exchange 2010, Exchange 2007, and Exchange Server 2003. Can be set by Office Outlook 2003 or earlier.

The following table describes various client and server combinations and the types of automatic replies that can be used in each scenario.

Client and server support for automatic replies

For a remote domain, you can specify one of the following options for sending automatic replies:

• Allow none   If you select this option, no automatic replies are sent to recipients in the remote domain.

• Allow external out-of-office messages only   If you select this option, only External automatic replies are sent to the remote domain.

• Allow external out-of-office messages and legacy out-of-office messages (configured by using Outlook 2003 or earlier clients, or configured on Exchange 2003 mailboxes)   If you select this option, both External and Legacy automatic replies are sent to the remote domain.

• Allow internal out-of-office messages, and legacy out-of-office messages (configured by using Outlook 2003 or earlier clients, or configured on Exchange 2003 mailboxes)   If you select this option, both Internal and Legacy automatic replies are sent to the remote domain.

Controlling NDR Information

As mentioned at the beginning of this topic, you can prevent NDRs from being sent to a remote domain. By blocking NDRs to a remote domain, you can prevent the information contained within the NDR message from leaving your organization, thereby limiting the knowledge a malicious user can obtain about your organization. However, this also prevents legitimate senders from receiving NDRs, resulting in confusion and lost productivity.

Exchange 2010 SP1 provides you with more granular control over the contents of an NDR destined for a remote domain. With Exchange 2010 SP1, you can now allow NDRs to a remote domain, while stripping any diagnostic information. This way, you can still prevent information about your Exchange deployment from leaving your organization while at the same time providing NDR notifications to external senders.

This feature is controlled with the new NDRDiagnosticInfoEnabled parameter of the Set-RemoteDomain cmdlet. Because this setting is configurable for each remote domain, you can have different settings based on your needs. For example, you can choose to remove the NDR diagnostic information for the default remote domain, but allow full NDR diagnostic information for the remote domains that represent your partners.

For more information about this new settings, see Set-RemoteDomain.

Remote Domains in Cross-Premises Deployments

Exchange 2010 SP1 supports cross-premises deployments where your Exchange organization is split between your on-premises servers and a cloud-based service such as Microsoft Office 365. In this deployment scenario, a remote domain object represents the part of your organization that exists in the cloud-based service. This remote domain is different from all the other remote domains you may have because it's considered an internal remote domain.

You can use either the Shell or the EMC to designate a remote domain as your Office 365 deployment. For detailed steps, see Configure Remote Domain Properties.

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