Contents
Install clamav ( anti-virus software )
1.Clam AntiVirus Install
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# dnf -y install clamav clamd clamav-update |
2.Edit Clam AntiVirus configuration file
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# vi /etc/clamd.d/scan.conf ●Line 14. # Default: disabled LogFile /var/log/clamd.scan ← Uncomment ●Line 77 # Default: disabled PidFile /run/clamd.scan/clamd.pid ← Uncomment ●Line 96 # Path to a local socket file the daemon will listen on. # Default: disabled (must be specified by a user) LocalSocket /run/clamd.scan/clamd.sock ← Uncomment ●Line 219 # Run as another user (clamd must be started by root for this option to work) # Default: don't drop privileges #User clamscan ← Add # at the beginning of the line and comment it out (to make it work with root privileges) |
3.Virus definition file update settings
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# vi /etc/freshclam.conf ●Line 75. 「DatabaseMirror database.clamav.net」Insert "#" at the beginning of a line 「DatabaseMirror db.jp.clamav.net」add #DatabaseMirror database.clamav.net DatabaseMirror db.jp.clamav.net ●Per line 151 「NotifyClamd /etc/clamd.d/scan.conf」add #NotifyClamd /path/to/clamd.conf NotifyClamd /etc/clamd.d/scan.conf |
4.Virus definition file update
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# freshclam ClamAV update process started at Wed Jul 13 09:54:26 2022 daily database available for download (remote version: 26565) Time: 3.0s, ETA: 0.0s [========================>] 56.03MiB/56.03MiB Testing database: '/var/lib/clamav/tmp.aca2d3f1fa/clamav-23517084062dbf640a1e7db5635d12b5.tmp-daily.cvd' ... Database test passed. daily.cvd updated (version: 26566, sigs: 1985565, f-level: 90, builder: raynman) main database available for download (remote version: 62) Time: 7.9s, ETA: 0.0s [========================>] 162.58MiB/162.58MiB Testing database: '/var/lib/clamav/tmp.aca2d3f1fa/clamav-31ab0225aac64a6d935b73fa24c3b497.tmp-main.cvd' ... Database test passed. main.cvd updated (version: 62, sigs: 6647427, f-level: 90, builder: sigmgr) bytecode database available for download (remote version: 333) Time: 0.5s, ETA: 0.0s [========================>] 286.79KiB/286.79KiB Testing database: '/var/lib/clamav/tmp.aca2d3f1fa/clamav-20ea46288aefc5e6fb938184abb83e92.tmp-bytecode.cvd' ... Database test passed. bytecode.cvd updated (version: 333, sigs: 92, f-level: 63, builder: awillia2) |
5.Start Clam AntiVirus
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# systemctl start clamd@scan ← clamd start # systemctl enable clamd@scan ← automatic clamd startup configuration Created symlink /etc/systemd/system/multi-user.target.wants/clamd@scan.service → /usr/lib/systemd/system/clamd@.service. # systemctl is-enabled clamd@scan enabled # systemctl status clamd@scan ← operation check ● clamd@scan.service - clamd scanner (scan) daemon Loaded: loaded (/usr/lib/systemd/system/clamd@.service; enabled; vendor pres> Active: active (running) since Fri 2022-09-02 13:46:45 JST; 24s ago Docs: man:clamd(8) man:clamd.conf(5) https://www.clamav.net/documents/ Main PID: 12358 (clamd) Tasks: 2 (limit: 10602) Memory: 1.2G CGroup: /system.slice/system-clamd.slice/clamd@scan.service mq12358 /usr/sbin/clamd -c /etc/clamd.d/scan.conf Sep 02 13:46:45 Lepard clamd[12358]: ELF support enabled. Sep 02 13:46:45 Lepard clamd[12358]: Mail files support enabled. Sep 02 13:46:45 Lepard clamd[12358]: OLE2 support enabled. Sep 02 13:46:45 Lepard clamd[12358]: PDF support enabled. Sep 02 13:46:45 Lepard clamd[12358]: SWF support enabled. Sep 02 13:46:45 Lepard clamd[12358]: HTML support enabled. Sep 02 13:46:45 Lepard clamd[12358]: XMLDOCS support enabled. Sep 02 13:46:45 Lepard clamd[12358]: HWP3 support enabled. Sep 02 13:46:45 Lepard clamd[12358]: Self checking every 600 seconds. Sep 02 13:46:45 Lepard systemd[1]: Started clamd scanner (scan) daemon. |
6.Perform virus scan
■Download a test virus and perform a virus scan
■Download a test virus and perform a virus scan
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# wget http://www.eicar.org/download/eicar.com # clamscan --infected --remove --recursive /root/eicar.com: Win.Test.EICAR_HDB-1 FOUND /root/eicar.com: Removed. ----------- SCAN SUMMARY ----------- Known viruses: 8632123 Engine version: 0.103.7 Scanned directories: 1 Scanned files: 10 Infected files: 1 Data scanned: 0.02 MB Data read: 0.01 MB (ratio 2.00:1) Time: 16.073 sec (0 m 16 s) Start Date: 2022:09:02 13:49:25 End Date: 2022:09:02 13:49:41 |
7.Deployment of virus scan auto-execution scripts
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# mkdir -p /var/www/system # cd /var/www/system Create clamscan.sh in /var/www/system with the following contents # vi /var/www/system/clamscan.sh #!/bin/bash PATH=/usr/bin:/bin # excludeopt setup excludelist=/var/www/system/clamscan.exclude if [ -s $excludelist ]; then for i in `cat $excludelist` do if [ $(echo "$i"|grep \/$) ]; then i=`echo $i|sed -e 's/^\([^ ]*\)\/$/\1/p' -e d` excludeopt="${excludeopt} --exclude-dir=$i" else excludeopt="${excludeopt} --exclude=$i" fi done fi # signature update freshclam # virus scan clamscan --recursive --remove ${excludeopt} / |
8.Virus scan exclusion directory settings
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# chmod 700 clamscan.sh # echo "/sys/" >> /var/www/system/clamscan.exclude # echo "/proc/" >> /var/www/system/clamscan.exclude |
Exclude sys and proc directories.
9.Scheduled virus scan
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# crontab -e 0 1 * * * /var/www/system/clamscan.sh > /dev/null 2>&1 |
10.Run a trial script and do a full scan (takes a while)
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# /var/www/system/clamscan.sh |
Mail Server Installation
1. Postfix Install
1.1 Install Postfix and build an SMTP server
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# dnf -y install postfix |
Confirm Postfix is installed
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# rpm -qa | grep postfix pcp-pmda-postfix-5.3.5-8.el8.x86_64 postfix-3.5.8-4.el8.x86_64 postfix-perl-scripts-3.5.8-4.el8.x86_64 |
1.2 Register Postfix to the service
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# systemctl enable postfix.service Created symlink /etc/systemd/system/multi-user.target.wants/postfix.service → /usr/lib/systemd/system/postfix.service. # systemctl is-enabled postfix.service enabled |
1.3 Backup postfix configuration files, main.cf and master.cf files
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# cp -p /etc/postfix/main.cf `date '+/etc/postfix/main.cf.%Y%m%d'` # cp -p /etc/postfix/master.cf `date '+/etc/postfix/master.cf.%Y%m%d'` |
1.4 Edit postfix configuration file
To prevent unauthorized mail relay, configure Postfix to require authentication for outgoing mail as well, using Dovecot's SASL function.
To prevent unauthorized mail relay, configure Postfix to require authentication for outgoing mail as well, using Dovecot's SASL function.
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# vi /etc/postfix/main.cf ●Added per line 96 #myhostname = virtual.domain.tld myhostname = mail.<domain> ●Add your domain name around line 103 #mydomain = domain.tld mydomain = <domain> ●Uncomment out per line 118 myorigin = $mydomain ●Change per line 135 inet_interfaces = all ●Added around line 183 Comment out around line 183 and add to line 184. #mydestination = $myhostname, localhost.$mydomain, localhost mydestination = $myhostname, localhost.$mydomain, localhost, $mydomain ●Added around line 287 #mynetworks = 168.100.189.0/28, 127.0.0.0/8 #mynetworks = $config_directory/mynetworks #mynetworks = hash:/etc/postfix/network_table mynetworks = 192.168.11.0/24, 127.0.0.0/8 ←192.168.11.0/24 to suit your environment ●Uncomment per line 440 Set the mail storage format. #home_mailbox = Mailbox home_mailbox = Maildir/ ●Added around line 447 #mail_spool_directory = /var/mail mail_spool_directory = /var/spool/mail ●Added around line 593 #smtpd_banner = $myhostname ESMTP $mail_name #smtpd_banner = $myhostname ESMTP $mail_name ($mail_version) smtpd_banner = $myhostname ESMTP unknown ●Add the following to the last line # Limit send/receive mail size to 10M message_size_limit = 10485760 # Limit mailbox size to 1G mailbox_size_limit = 1073741824 # SMTP-Auth setting smtpd_sasl_type = dovecot smtpd_sasl_path = private/auth smtpd_sasl_auth_enable = yes smtpd_sasl_security_options = noanonymous smtpd_sasl_local_domain = $mydomain smtpd_recipient_restrictions = permit_mynetworks, permit_auth_destination, permit_sasl_authenticated, reject |
Allow SMTP port (port 25)
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# firewall-cmd --add-service=smtp --permanent success # firewall-cmd --reload success |
1.5 Start Postfix
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# systemctl enable --now postfix # systemctl start --now postfix |
2.Dovecot Install
2.1 dovecot install
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# dnf -y install dovecot |
2.2 Edit dovecot.conf file
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# cp -p /etc/dovecot/dovecot.conf `date '+ /etc/dovecot/dovecot.conf.%Y%m%d'` # vi /etc/dovecot/dovecot.conf ●Add around line 25 # protocols = imap pop3 lmtp protocols = imap pop3 ●Line 30 : Uncomment # Remove [::] if listening for IPv4 only listen = *, :: |
2.3 Edit 10-auth.conf file
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# vi /etc/dovecot/conf.d/10-auth.conf ●Line 10 : Uncomment and change If plain text authentication is also allowed disable_plaintext_auth = no ●Line 100 : Additional entry auth_mechanisms = plain login |
2.3 Edit 10-mail.conf file
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# vi /etc/dovecot/conf.d/10-mail.conf ●Line 31 : Addition mail_location = maildir:~/Maildir |
2.4 Edit 10-master.conf file
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# vi /etc/dovecot/conf.d/10-master.conf ●Lines 107-109 : Uncomment and add # Postfix smtp-auth unix_listener /var/spool/postfix/private/auth { mode = 0666 user = postfix group = postfix } |
2.5 Edit 10-ssl.conf file
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# vi /etc/dovecot/conf.d/10-ssl.conf ●Per line 8 Change "ssl = required" to "ssl = yes" ssl = yes |
2.6 Register dovecot as a service and start it
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# systemctl enable dovecot.service Created symlink /etc/systemd/system/multi-user.target.wants/dovecot.service → /usr/lib/systemd/system/dovecot.service. # systemctl is-enabled dovecot.service Enabled # systemctl start dovecot.service |
2.7 Permission port opening for POP/IMAP service with firewalld
POP is [110/TCP], IMAP is [143/TCP].
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# firewall-cmd --permanent --add-service=pop3 # firewall-cmd --permanent --add-service=imap # firewall-cmd --reload |
3.Create mail user and check operation
3.1 advance preparation
①Pretreatment for new users
When a new user is added, set up the system to automatically send and receive e-mail.
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# mkdir -p /etc/skel/Maildir/{new,cur,tmp} # chmod -R 700 /etc/skel/Maildir/ # echo "~/Maildir/"> /etc/skel/.forward # chmod 600 /etc/skel/.forward |
Configure the already created users to be able to send and receive e-mail.
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# mkdir -p /home/huong/Maildir/{new,cur,tmp} # chown -R huong:huong /home/huong/Maildir/ # chmod 700 /home/huong/Maildir # chmod 700 /home/huong/Maildir/{new,cur,tmp} |
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Mail client installation # dnf -y install mailx # echo 'export MAIL=$HOME/Maildir' >> /etc/profile.d/mail.sh Add user "linux" # useradd linux # passwd linux Change password for user linux. New password: Retype new password: passwd: all authentication tokens updated successfully. |
3.3 operation check ①
①Log in as an email user and send a test email.
①Log in as an email user and send a test email.
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# su - linux $ mail linux@localhost Subject: Test Mail test mail . ← To end the text, type "." Enter. EOT $ mail Heirloom Mail version 12.5 7/5/10. Type ? for help. "/home/linux/Maildir": 1 message 1 new >N 1 linux@korodes.com Fri Sep 2 14:39 17/511 "Test Mail" & 1 Message 1: From linux@korodes.com Fri Sep 2 14:39:16 2022 Return-Path: <linux@korodes.com> X-Original-To: linux@localhost Delivered-To: linux@localhost Date: Fri, 02 Sep 2022 14:39:16 +0900 To: linux@localhost Subject: Test Mail User-Agent: Heirloom mailx 12.5 7/5/10 Content-Type: text/plain; charset=utf-8 From: linux@korodes.com Status: R test mail & Enter "q" to exit |
3.4 operation check ②
Set up and confirm your account in Mozilla Thunderbird. This time we will set it up with the general user "huong".
Set up and confirm your account in Mozilla Thunderbird. This time we will set it up with the general user "huong".
①Start Thunderbird, and click "Tools", "Account Settings".
②「Account Actions」「Add Mail Account」
③Your full name : Any name
Email addtess : "huong@korodes.com" that I just added.
Password : Password for user huong
Click on "Configure manually"
④Set "INCOMMING SERVER" and "OUTGOING SERVER" as shown below and click "Re-test".
⑤The following settings were found by probinfg the given server
After clicking "Done", the following "Warning" is displayed, but there is no problem, so click "Confirm".
⑥Click "Finish" when "Account syccessfuly created" is displayed.
Mail server : Postfix + Clamav + Amavisd + SpamAssassin
1.Real-time scanning of e-mails
①Install Amavisd and Clamav Server
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# dnf config-manager --set-enabled ol8_codeready_builder # dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm # dnf config-manager --set-enabled epel # dnf -y install amavisd-new clamd perl-Digest-SHA1 perl-IO-stringy |
➁Configuration File Editing
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# vi /etc/clamd.d/scan.conf ●Line 77: Change PidFile /var/run/clamd.scan/clamd.pid ●Line 81: Uncomment TemporaryDirectory /var/tmp ●Line 96: Change LocalSocket /var/run/clamd.scan/clamd.sock |
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# touch /var/log/clamd.scan # chown clamscan. /var/log/clamd.scan # systemctl enable clamd@scan |
➂Setup and start Amavisd
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# vi /etc/amavisd/amavisd.conf ●Delete # at the beginning of the line per line 13 @bypass_spam_checks_maps = (1); # controls running of anti-spam code ● Line 23: Change to own domain name $mydomain = 'domain name'; ●Comment out per line 28 #$QUARANTINEDIR = undef; # -Q ●Comment out per line 125 # $virus_admin = undef; # notifications recip ●Line 158: Uncomment and change to own host name $myhostname = 'mail.domain'; # systemctl start amavisd # systemctl enable amavisd Created symlink /etc/systemd/system/multi-user.target.wants/amavisd.service → /usr/lib/systemd/system/amavisd.service. |
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# vi /etc/postfix/main.cf # Add to the last line content_filter=smtp-amavis:[127.0.0.1]:10024 # vi /etc/postfix/master.cf # Add to the last line smtp-amavis unix - - n - 2 smtp -o smtp_data_done_timeout=1200 -o smtp_send_xforward_command=yes -o disable_dns_lookups=yes 127.0.0.1:10025 inet n - n - - smtpd -o content_filter= -o local_recipient_maps= -o relay_recipient_maps= -o smtpd_restriction_classes= -o smtpd_client_restrictions= -o smtpd_helo_restrictions= -o smtpd_sender_restrictions= -o smtpd_recipient_restrictions=permit_mynetworks,reject -o mynetworks=127.0.0.0/8 -o strict_rfc821_envelopes=yes -o smtpd_error_sleep_time=0 -o smtpd_soft_error_limit=1001 -o smtpd_hard_error_limit=1000 |
# systemctl restart postfix
⑤I sent a test email to myself in Thunderbird, and in the header display part of the received email, I see the following
X-Virus-Scanned: amavisd-new at korodes.com
X-Virus-Scanned: amavisd-new at korodes.com
2.Anti-Spam Measures for Emails
①SpamAssassin installed to prevent spam
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# dnf -y install spamassassin spamass-milter-postfix # systemctl start spamassassin # systemctl enable spamassassin Created symlink /etc/systemd/system/multi-user.target.wants/spamassassin.service → /usr/lib/systemd/system/spamassassin.service. |
②SpamAssassin Settings
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# vi /etc/mail/spamassassin/v310.pre ●Delete # at the beginning of the line per line 24 loadplugin Mail::SpamAssassin::Plugin::DCC |
③SpamAssassin configuration file modernization script
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# cd /var/www/system # vi /var/www/system/spamassassin-update.sh #!/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 fi fi cp user_prefs user_prefs.org |
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# chmod 700 /var/www/system/spamassassin-update.sh # /var/www/system/spamassassin-update.sh |
Check that the SpamAssassin configuration file is created in the /etc/mail/spamassassin directory with the date of the day.
SpamAssassin configuration file is created as of the current date.
SpamAssassin configuration file is created as of the current date.
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# ls -l /etc/mail/spamassassin total 1512 drwxr-xr-x 2 root root 40 Sep 2 14:58 channel.d -rw-r--r-- 1 root root 985 Apr 1 04:38 init.pre -rw-r--r-- 1 root root 499337 Sep 2 15:23 local.cf drwx------ 2 root root 6 Apr 1 04:38 sa-update-keys -rw-r--r-- 1 root root 62 Apr 1 04:38 spamassassin-default.rc -rwxr-xr-x 1 root root 35 Apr 1 04:38 spamassassin-helper.sh -rw-r--r-- 1 root root 55 Apr 1 04:38 spamassassin-spamc.rc -rw-r--r-- 1 root root 499289 Dec 29 2021 user_prefs -rw-r--r-- 1 root root 499289 Sep 2 15:23 user_prefs.org -rw-r--r-- 1 root root 2523 Sep 2 15:21 v310.pre -rw-r--r-- 1 root root 1194 Apr 1 04:38 v312.pre -rw-r--r-- 1 root root 2416 Apr 1 04:38 v320.pre -rw-r--r-- 1 root root 1237 Apr 1 04:38 v330.pre -rw-r--r-- 1 root root 1020 Apr 1 04:38 v340.pre -rw-r--r-- 1 root root 1114 Apr 1 04:38 v341.pre -rw-r--r-- 1 root root 1313 Apr 1 04:38 v342.pre -rw-r--r-- 1 root root 1264 Apr 1 04:38 v343.pre |
Set up cron to automatically run a script daily that updates the SpamAssassin configuration file
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# crontab -e 0 2 * * * /var/www/system/spamassassin-update.sh > /dev/null 2>&1 |
④Integrate SpamAssassin into Postfix
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# vi /etc/postfix/master.cf ●Per line 12. Add "#" to the beginning of line 12 and add SpamAssassin setting to line 13 # smtp inet n - n - - smtpd smtp inet n - n - - smtpd -o content_filter=spamassassin ●Add to last line smtp-amavis unix - - n - 2 smtp -o smtp_data_done_timeout=1200 -o smtp_send_xforward_command=yes -o disable_dns_lookups=yes 127.0.0.1:10025 inet n - n - - smtpd -o content_filter= -o local_recipient_maps= -o relay_recipient_maps= -o smtpd_restriction_classes= -o smtpd_client_restrictions= -o smtpd_helo_restrictions= -o smtpd_sender_restrictions= -o smtpd_recipient_restrictions=permit_mynetworks,reject -o mynetworks=127.0.0.0/8 -o strict_rfc821_envelopes=yes -o smtpd_error_sleep_time=0 -o smtpd_soft_error_limit=1001 -o smtpd_hard_error_limit=1000 spamassassin unix - n n - - pipe user=nobody argv=/usr/bin/spamc -e /usr/sbin/sendmail.postfix -oi -f ${sender} ${recipient} |
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# systemctl restart postfix |
⑥If you send an e-mail to yourself in Thunderbird with the following information in the body, the following will appear in the header.
XJS*C4JDBQADN1.NSBN3*2IDNEN*GTUBE-STANDARD-ANTI-UBE-TEST-EMAIL*C.34X
