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LLL

.Email spam protection

2.1 SpamAssassin, spamass-milter, and postfix settings

①SpamAssassin・spamass-milter Install

# dnf -y install spamassassin spamass-milter-postfix

➁SpamAssassin start

# systemctl start spamassassin

➂SpamAssassin Settings

# vi /etc/mail/spamassassin/v310.pre

Per Line 24 : Remove # at the beginning of the line

loadplugin Mail::SpamAssassin::Plugin::DCC

④SpamAssassin configuration file modernization script

# cd /var/www/system

# vi spamassassin-update.sh

Describe the following information

#!/bin/bash

cd /etc/mail/spamassassin

wget -q https://github.com/kittyfreak/spamassassin_user_prefs/archive/refs/heads/main.zip

[ $? -ne 0 ] && exit

unzip main.zip >/dev/null 2>&1

[ $? -ne 0 ] && exit

rm -f main.zip

mv spamassassin_user_prefs-main/user_prefs .

rm -rf spamassassin_user_prefs-main

diff user_prefs user_prefs.org > /dev/null 2>&1

if [ $? -ne 0 ]; then

cp user_prefs local.cf

echo "report_safe 0" >> local.cf

echo "rewrite_header Subject ***SPAM***" >> local.cf

# SpamAssassin restart

if [ -f /etc/rc.d/init.d/spamassassin ]; then

/etc/rc.d/init.d/spamassassin restart > /dev/null

else

systemctl restart spamassassin > /dev/null

cp user_prefs user_prefs.org

Grant execute permission to the spamassassin-update script and run it

# /var/www/system/spamassassin-update.sh

Confirm that the SpamAssassin configuration file (local.cf) has been created in the /etc/mail/spamassassin directory with the date of the day

# ls -l /etc/mail/spamassassin

total 1524

drwxr-xr-x 2 root root 40 Oct 31 14:21 channel.d

-rw-r--r-- 1 root root 985 Apr 19 2022 init.pre

-rw-r--r-- 1 root root 500636 Oct 31 14:31 local.cf

drwx------ 2 root root 6 Apr 19 2022 sa-update-keys

-rw-r--r-- 1 root root 62 Apr 19 2022 spamassassin-default.rc

-rwxr-xr-x 1 root root 35 Apr 19 2022 spamassassin-helper.sh

-rw-r--r-- 1 root root 55 Apr 19 2022 spamassassin-spamc.rc

-rw-r--r-- 1 root root 500588 Apr 30 2023 user_prefs

-rw-r--r-- 1 root root 500588 Oct 31 14:31 user_prefs.org

-rw-r--r-- 1 root root 2523 Oct 31 14:30 v310.pre

-rw-r--r-- 1 root root 1194 Apr 19 2022 v312.pre

-rw-r--r-- 1 root root 2416 Apr 19 2022 v320.pre

-rw-r--r-- 1 root root 1237 Apr 19 2022 v330.pre

-rw-r--r-- 1 root root 1020 Apr 19 2022 v340.pre

-rw-r--r-- 1 root root 1114 Apr 19 2022 v341.pre

-rw-r--r-- 1 root root 1313 Apr 19 2022 v342.pre

-rw-r--r-- 1 root root 1264 Apr 19 2022 v343.pre

Set up cron to automatically run a script daily that updates the SpamAssassin configuration file

# crontab -e

0 2 * * * /var/www/system/spamassassin-update.sh > /dev/null 2>&1

⑤spamass-milter startup and automatic startup settings

# systemctl start spamass-milter

# systemctl enable spamass-milter

Created symlink /etc/systemd/system/multi-user.target.wants/spamass-milter.service → /usr/lib/systemd/system/spamass-milter.service.

⑥Postfix and spamass-milter integration settings

# vi /etc/postfix/main.cf

Add the following

milter_default_action = tempfail

smtpd_milters = unix:/var/run/clamav-milter/clamav-milter.socket,unix:/run/spamass-milter/postfix/sock ※既にclamav-milterが定義されている場合

non_smtpd_milters = unix:/var/run/clamav-milter/clamav-milter.socket,unix:/run/spamass-milter/postfix/sock ※既にclamav-milterが定義されている場合

⑦Restart postfix

# systemctl restart postfix

⑧Procmail Settings
Create procmail configuration file

# vi /etc/postfix/main.cf

Per Line 469 : Add

#mailbox_command = /some/where/procmail

#mailbox_command = /some/where/procmail -a "$EXTENSION"

mailbox_command = /usr/bin/procmail

Postfix Settings Reflected

# systemctl restart postfix

2.2 Spam mail sorting settings

Mail marked as spam in the mail header by SpamAssassin will be delivered to a spam-only mailbox, while other mail will be delivered to a normal mailbox.

①Create a dedicated spam mailbox
For existing users, add a spam-only mailbox to their mailboxes.
For new users, a spam-only mailbox will be automatically created when a user is added.

①Created script to create spam-only mailboxes

# vi spamfolder-create

#!/bin/bash

for user in `ls /home`

id -u $user > /dev/null 2>&1

if [ $? -eq 0 ] && [ ! -d /home/$user/Maildir/.Spam/new ]; then

mkdir -p /home/$user/Maildir/.Spam/new

mkdir -p /home/$user/Maildir/.Spam/cur

mkdir -p /home/$user/Maildir/.Spam/tmp

chmod -R 700 /home/$user/Maildir/.Spam

chown -R $user. /home/$user/Maildir/.Spam

echo $user

done

Run script to create spam-only mailboxes

# bash spamfolder-create

huong

linux

Measures against new users
Automatic spam-only mailbox creation when adding new users

# mkdir -p /etc/skel/Maildir/.Spam/{new,cur,tmp}

# chmod -R 700 /etc/skel/Maildir/.Spam

➁spam mail sorting
Emails identified as spam by SpamAssassin are delivered to a spam-only mailbox.

# vi /etc/procmailrc

Add the following to the end

*^X-Spam-Flag: YES

$HOME/Maildir/.Spam/

➂spamass-milter confirmation
When you send a blank email to yourself, the following message is appended to the header of the received email
X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on Lepard

LLL