Prerequisites
Deploy an Ubuntu cloud server instance at Vultr.
Install Postfix mail transfer agent.
Create a sudo user.
Verify the server has outbound port 25 open.
1. Install SpamAssassin
Connect to your server with SSH.
Install SpamAssassin.
$ sudo apt-get update
$ sudo apt-get install spamassassin spamc -y Configure SpamAssassin
Assign the spamd user account to SpamAssassin and set the log and default home directories.
Edit the configuration settings.
$ sudo nano /etc/default/spamassassin
Find the line:
ENABLED=1
Uncomment it by removing # and change the value from 1 to 0.
ENABLED=0
Find the line:
OPTIONS="--create-prefs --max-children 5 --helper-home-dir"
Change it to include the SpamAssassin user account and log files directory.
OPTIONS="--create-prefs --max-children 5 --username spamd --helper-home-dir /home/spamd/ -s /home/spamd/spamd.log"
Find the line:
CRON=0
Change the value from 0 to 1.
CRON=1
Save and close the file.
Make a backup of the SpamAssassin local configuration file.
$ sudo mv /etc/spamassassin/local.cf /etc/spamassassin/local.cf.bk