5.2 Scenario 1: Routing Mail for a Domain

SMTP works by sending mail messages between different hosts. By default, mail is not sent between networks or domains, but is instead sent between physical hosts that process mail for a network or a domain. Under strict definition, the sending and receiving hosts are supposed to identify themselves explicitly, such as user@greywolf.unoverica.com or user@prophet.unoverica.com.

However, very few organizations use fully-qualified host names in the "To:" and "From:" fields of their mail messages. Most organizations prefer to use the domain name alone for out- bound and in-bound mail. For example, mail addresses are typically along the lines of user@unoverica.com instead of user@host.unoverica.com. Figure 5.2 below illustrates this scenario:

Figure 5.2 In this scenario, the mail server is configured to accept mail for an entire domain name, instead of for a specific hostname.

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NOTE: This discussion assumes that your organization maintains a full-time or on-demand connection to the Internet, and that you are capable of routing mail directly between your site and remote networks. If your organization does not maintain a direct Internet connection but instead uses an external site for mail routing, then you should not implement this architecture. Instead, refer to section 5.3 Scenario 2: Routing Mail Through an External Site for instructions on how to configure Unoverica Message Transport to work with an external relay site.

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There are four steps that you must follow in order to implement this setup successfully:

1. Enable DNS client services on the local NetWare server. This is achieved by creating a RESOLV.CFG file if one does not already exist, and by enabling the use of DNS lookups within Unoverica Message Transport's configuration tool. For more information on this subject, refer to section 5.2.1 Enabling the DNS Client.
   
   
2. Add MX records to the DNS server for your domain that point back to the local NetWare server. This allows remote sites to locate the mail server to use when sending mail to your domain name. For more information on the MX records that need to be created, refer to section 5.2.2 Creating "MX" Records for the Domain.
   
   
3. Configure Unoverica Message Transport to accept mail for the domain. For instructions on how to do this, refer to section 5.2.3 Adding the Domain to Unoverica Message Transport.
   
   
4. Configure your mail clients and Unoverica Message Transport to mark outbound mail as being from user@domain.com, instead of user@host.domain.com. For more information on this subject, refer to section 5.2.4 Changing the From: Headers.
   

Once these steps have been completed and the DNS updates have been propagated throughout the Internet, then you should be able to receive mail addressed to your local domain name.

STEP: To continue to the next step in the configuration process, go to section 5.2.1 Enabling the DNS Client.

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