N) Spam filtering

RSpamD is an advanced spam filtering system and email processing framework that allows evaluation of messages by a number of rules including regular expressions, statistical analysis and custom services such as URL black lists. Each message is analysed by Rspamd and given a verdict that might be used by MTA for further processing (e.g. to reject a message, or add a special header indicating spam) along with other information, such as possible DKIM signature or modifications suggested for a message.

My VPS is pretty ancient and the CPU does not support sse4_2, instructions, so i had to disable hyperscan use flag by writing the following /etc/portage/package.use/rspamd file:

rspamd

mail-filter/rspamd  -hyperscan

Now simply emerge it:

emerge -vp rspamd dev-db/redis

rspamd requires redis, but somehow it doesn't pull it directly.

Create /etc/rspamd/local.d/actions.conf:

actions.conf

# Basic action thresholds
reject = 15;        # Reject obvious spam
add_header = 6;     # Add spam headers
greylist = 4;       # Temporary delay suspicious mail

Configure redis /etc/rspamd/local.d/redis.conf:

# Redis connection for statistics and caching
servers = "127.0.0.1:6379";

Setup a controller password for the web interface:

rspamadm pw

Create /etc/rspamd/local.d/worker-controller.inc:

worker-controller.inc

# Replace with your generated password
password = "$2$your_generated_password_here";

Setup redis at least in a basic and secure way /etc/redis/redis.conf:

redis.conf

# Bind only to localhost for security
bind 127.0.0.1 ::1
# Set memory limit
maxmemory 500mb
maxmemory-policy volatile-ttl

Add milter integration to your Postfix configuration in /etc/postfix/main.cf:

# Enable Rspamd milter
smtpd_milters = inet:localhost:11332
milter_default_action = accept
milter_protocol = 6

Configure Rspamd proxy worker in /etc/rspamd/local.d/worker-proxy.inc:

worker-proxy.inc

# Enable milter mode for Postfix integration
milter = yes;
timeout = 120s;
upstream "local" {
  default = yes;
  self_scan = yes;  # Scan messages directly
}

Ensure all the services are running and setup to start on boot:

for i in rspamd redis postfix
do
 rc-update add $i default
 /etc/init.d/$i restart
done

Work in progress!!