You can integrate the message security service into your current mail system to filter intradomain traffic. This appendix explains intradomain routing and how your Sendmail server interacts with intradomain routing.

A traditional mail server configuration is a single email server name for both incoming email (POP/IMAP) and outgoing email (SMTP). In the examples that follow, this server will be referred to as mail.jumboinc.com.

When the message security service is activated, all incoming emails from users outside of your mail server are routed first through the message security service servers, and then to mail.jumboinc.com. This means the message security service processes all email for junk and virus filtering, and wireless messaging.

However, when a user on your mail server sends to another user on the same mail server, the mail server generally drops the message directly into the receiving user's queue. This bypasses the routing of email through the message security service servers. So emails are not filtered for junk, virus, or wireless.

For the examples below, mail.jumboinc.com is the incoming mail server name and smtp.jumboinc.com is the outgoing email server name.

A new server must to be set up that will be used for all outgoing email. There are no special server settings that need to be made. Care should be taken to ensure that the new email server (smtp.jumboinc.com) uses a DNS server that shows the MX record for jumboinc.com to be at the message security service. The clients will all need to be reconfigured to use smtp.jumboinc.com as the outgoing email server.

This solution requires the use of two network interface cards or virtual IPs. It is recommended that you create a “jail” which runs a second instance of your MTA.