Redirect system emails to an external email address

By default, system emails are sent to the local root account. These emails can provide alerts and tips on the system health. This guide help you setup a redirection to an external email address (sysadmin’s one) for these emails.

This howto is tested on:

• Debian 10.0 Buster

Settings

Set the external email address to which system emails are sent:

sysadminEmail="account@gmail.com"

Installation

Detect if sudo is available (“command” is used if not):

cmdProxy='command'
command type -f 'sudo' &>'/dev/null' && cmdProxy='sudo'

SMTP server setup

Install the required software:

${cmdProxy} apt install 'exim4' 'bsd-mailx'

Use the current full hostname as the system mail domain (best default for a commercial dedicated server):

command hostname --fqdn \
    | ${cmdProxy} tee '/etc/mailname'

Setup the Exim 4 SMTP server as directly connected to the Internet (no relay SMTP used):

${cmdProxy} sed -i \
    -e "s|dc_eximconfig_configtype=.*\$|dc_eximconfig_configtype='internet'|" \
    -e "s|dc_other_hostnames=.*\$|dc_other_hostnames='$(command hostname --fqdn)'|" \
    -e "s|dc_use_split_config=.*\$|dc_use_split_config='true'|" \
  '/etc/exim4/update-exim4.conf.conf'

Update Exim 4 configuration:

${cmdProxy} update-exim4.conf

Reload Exim 4 configuration:

${cmdProxy} systemctl restart 'exim4'

System emails redirection

Redirect emails sent to the local root account to the chosen email address:

${cmdProxy} sed -i \
    -e "s/^root:.*\$/root: ${sysadminEmail}/" \
  '/etc/aliases'

Reload the email aliases configuration:

${cmdProxy} newaliases