Synopsis: Internal User > Load Balancer > MTA Outbound Relay 1 or 2 > Internet
Messages addressed from an internal user to an external user (that is, users not on the same email system) go to a load balancer. The load balancer shields the email user from the underlying site architecture and helps provide a highly available email service. The load balancer sends the message to either MTA Outbound Relay 1 or 2. The outbound relay reads the address and determines that the message is addressed to an external user. The outbound relay sends the message to an MTA on the Internet.