Redirect local emails to a remote email account

My previous post is a guide for setting up exim4, an SMTP mail server, to use Gmail as a smarthost. One reason for setting up a mail server is to redirect my local root emails to an Internet email account that I actually monitor. In this way, I won't miss any security alert sent to the local root mailbox.

This post shows you how to set up email redirection. The instructions are similar for various mail servers: exim4, Postfix, or sendmail.

1. Set up an SMTP server.
2. Edit /etc/aliases as root.

   mailer-daemon: postmaster
   postmaster: root
   nobody: root
   hostmaster: root
   usenet: root
   news: root
   webmaster: root
   www: root
   ftp: root
   abuse: root
   noc: root
   security: root
   root: peter
   

   To the left of the colon is the mail alias defined on the local machine. You can send email to a local email alias, say security and the message will be redirected to the account(s) specified to the right of the colon.

   In many default mail server configurations, emails to any alias are forwarded to root. But often root itself is not redirected to a regularly monitored email account.

3. Redirect root.

   Replace the root: peter line with the line below using your personal email address:

   root: yourAddress@gmail.com
   

4. Rebuild alias database.

   $ newaliases
   

   For sendmail, and Postfix, after you modify the alias file, you need to run the newaliases command to rebuild the mail alias database. For exim4, this step is not required because it relies solely on the alias file and NO database.

To test, send root an email, and verify that the message is delivered to the target remote email account.

$ echo 'Code red'| mail -s 'Hacker Alert' root