Configure nullmailer with a relay host

edafe.de/nullmailer If you wish to receive status updates from your Debian or Ubuntu system, you need to install and configure a mail transfer agent (MTA). nullmailer is a relay-only forwarding MTA that can be used as an alternative to more complex MTAs, such as Exim, Sendmail or Postfix. A relay host, also referred to as a smarthost, can be defined as an email server for outgoing mail that is being afforded a good reputation by its peers. In this example, we use Fastmail because email deliverability depends on a number of different factors. Configuration of nullmailer with Email Service Providers (ESPs) other than Fastmail should be similar, given that all ESPs implement the Simple Mail Transfer Protocol (SMTP). Step 1 Generate an app password Log into your Fastmail account and set up a new app password for SMTP authentication. Create an alias Set up a dedicated Fastmail alias to receive incoming messages. Step 2 Use copy and paste to enter the following commands. Be careful not to miss any punctuation. Create the new directory /etc/nullmailer and the file /etc/nullmailer/adminaddr. $ sudo mkdir /etc/nullmailer && sudo nano /etc/nullmailer/adminaddr The Fastmail alias you created in Step 1 should be the only entry in /etc/nullmailer/adminaddr. target.email@fastmail.com Step 3 Install the required packages. $ sudo apt-get install --yes nullmailer mailutils Step 4 Enter the system mailname. If you are setting up on a home network, you should use home.arpa as the domain name. Configuring nullmailerMailname of your system:tux.home.arpaOk Configuring the smarthost Configure nullmailer to use the Fastmail SMTP server as a smarthost. Use your Fastmail username and the app password from Step 1. Configuring nullmailer Smarthosts: smtp.fastmail.com smtp --port=587 --auth-login --starttls --user=linus.torvalds@fastmail.com --pass=password Ok Step 5 Test your configuration with the following command. $ echo "Test mail from nullmailer on tux.home.arpa to the local root user and forwarded on to Fastmail" | mail -s "Test nullmailer" root Check your inbox! Step 6 You can reconfigure nullmailer at any time by issuing the following comand. $ sudo dpkg-reconfigure nullmailer