Prerequisites for an e-mail router

This topic tells what you should do before you configure an e-mail router.

Before you configure an e-mail router, consider the following aspects:

• The intermediate server does not have to be an i5/OS^® operating system. The mail router only requires a host table that contains all host servers to which it needs to route e-mail. If an i5/OS operating system is the mail router, it does not require any particular system level.

• You can set up only one intermediate server for routing between the source and target server. You cannot nest mail routers.

• Simple Mail Transfer Protocol (SMTP) must be able to get an IP address for the mail router when it starts, either from the local host table or through the Domain Name System (DNS) server. If SMTP cannot get an IP address for the mail router, then SMTP runs without using a router.

• The SMTP client firewall support uses the mail router to forward e-mail that is destined for a host outside the local (protected) domain. In order to deliver e-mail, the mail router must be a server that is authorized to forward e-mail through the firewall. Also, mail recipients whose domain is not on the i5/OS operating system go through the router when you turn on the SMTP firewall support. i5/OS V5R1 and later supports multiple local domains. You can configure multiple domains that do not send mail through the firewall.