Install and configure Exim 4 SMTP Relay via Smarthost on Ubuntu

Email is far from a perfect communication medium for all use cases but it is still a really good option for low volume alerts from your security monitoring gear.

In this article we will quickly show how to set up Exim 4 as a basic mail relay on a Ubuntu server.

Exim Installation

$ sudo apt-get install exim4

Configuration

On Debian and Ubuntu, Exim 4 is configured most easily using a template system. This is found in /etc/exim4. The basic idea is to change the /etc/exim4/update-exim4.conf.conf file and then run the template generation over it.

Smarthost

The following configuration sets up Exim to send via a Smarthost, i.e. another mail server. This is most common on an internal network. In this case, the host nsm.4armed.com is being configured to send via smarthost.4armed.com. You should obviously configure these values accordingly.

dc_eximconfig_configtype='satellite'
dc_other_hostnames='nsm'
dc_local_interfaces='127.0.0.1 ; ::1'
dc_readhost='4armed.com'
dc_relay_domains=''
dc_minimaldns='false'
dc_relay_nets=''
dc_smarthost='smarthost.4armed.com'
CFILEMODE='644'
dc_use_split_config='false'
dc_hide_mailname='true'
dc_mailname_in_oh='true'
dc_localdelivery='mail_spool'

Now update the configuration files and restart Exim.

$ cd /etc/exim4
$ sudo update-exim4.conf
$ sudo /etc/init.d/exim4 restart

Send yourself a test.

$ echo "This is a test" | mailx -s "Test Message" -v yourname@yourdomain.com
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Marc Wickenden

Technical Director at 4ARMED, you can blame him for our awesome technical skills and business-led solutions. You can tweet him at @marcwickenden.

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