Every time I use sudo on the command line I get an email. This way I can always know if someone has attempted to run sudo on my computer. Plus; combined with Gmail, it makes for an excellent audit trail.
I set it up following the guide here; Sudo email setup, original post
Or you can do the below.
I wanted to get an email from the computer every time sudo was used successfully or not. You need an MTA or mail transport agent. I have Postfix on my computer. There may be other ways to send an email; but that is beyond the scope of this post. I will show you what I did and I will assume you have an MTA already setup.
The first command tells visudo where to create the file. All edits should go to /etc/sudoers.d because this will make software updates more sane.
sudo visudo -f /etc/sudoers.d/mail_sudoers
File should look exactly like below. Be sure to include double quotes.
Defaults mail_always Defaults mailto="firstname.lastname@example.org"
Visudo will set the proper permissions for you. No need for chmod if you are using Ubuntu 16.10 or later.
man sudo, visudo, sudoers will help greatly.
I’ve included a screenshot of what the email looks like. Naturally the important bits after the @ have been removed.