In this example, one IBM® Lotus® Domino™ server, Mail2, routes messages from the Acme organization destined for other Internet domains (external addresses) and a second Domino server, Mail3, receives mail addressed to the Acme Internet domain (acme.com). Mail2 has the field "SMTP used when sending messages outside of the local Internet domain" enabled on the Router/SMTP-Basics tab of the Configuration Settings document that applies to the server. Mail3 has the SMTP listener task enabled on the Basics tab of its Server document, and has an MX (mail exchanger) record in the external DNS.

If a user on the Acme internal mail server, Mail1, sends a message to an external address -- one with a domain other than acme.com -- the server routes the message to Mail2, which can route mail to external domains. Any mail from an external Internet domain -- one other than acme.com -- is routed to Mail3, which is listed in the DNS as the MX host for acme.com. Once the mail reaches Mail3, the server routes it to its destination.

The internal mail server, Mail1, can route Internet mail to the server with SMTP enabled for external mail (Mail2) either via IBM® Lotus® Notes® routing, with a Foreign SMTP Domain document and SMTP Connection document linking to Mail2, or via SMTP routing, with Mail2 configured as the relay host.

Configuring these servers requires:

• Enabling "SMTP used when sending messages outside of the local Internet domain" for Mail2.
• Enabling the SMTP listener task for Mail3.
• Setting up DNS correctly to list Mail3 as the MX host for the acme.com domain for inbound mail.
• Either enabling "SMTP allowed outside of the local Internet domain" for Mail1 and listing Mail2 as the relay host, or creating a Foreign SMTP Domain document and SMTP Connection document that define the route to Mail2.

Sample mail routing configurations

Glossary