Click here for "Error Codes for Commercial Air Conditioners".

Ubuntu22.04 Server : Anti-virus , Mail Server

1.Introduced Clamav antivirus software

1.1 Install

The clamav-related configuration files are installed in the /etc/clamav/ folder.

1.2 Virus Definition Update

⚫Modify configuration file

1.3 Virus Check Confirmation

①Run virus check manually

Infected files: 0 No virus.

②Virus detection by downloading test viruses
Download a harmless virus and test it for detection.
Log in as a general user and check

The virus is notified with the message "FOUND" and "Infected files: 1". Also, since the "--remove" option is attached, the test virus has been removed.

1.4 Create a script file to do a full scan

①Contents of (new)

②grant execution authority

③Create a folder for virus quarantine
LibClamAV Warning: cli_scanxz: decompress file size exceeds limits - only scanning 27262976 bytes
If you see the above

Run with the options "--max-filesize=200M" "--max-scansize=200M"

⑤Scheduled virus scan execution with cron

2.Email software installation

2.1 Postfix : Installation/Configuration

Install Postfix and build an SMTP server; SMTP uses 25/TCP.
To prevent unauthorized mail relay, use the SASL function of Dovecot, described below, and configure Postfix so that authentication is also required for sending mail.


Installation Status Screen
You will be asked to select a general configuration setting, select "No Configuration" to set it manually later

②Configuration File Editing

Editorial content

③ edit

Editorial content

④Set content reflects

2.2 Dovecot : Installation/Configuration

Install Dovecot and build a POP/IMAP server, using 110/TCP for POP and 143/TCP for IMAP
①Configure Dovecot to provide SASL functionality for Postfix

②Settings reflect

2.3 Email User Account Registration

Register a user account for e-mail.
This setting is for when a user account on the OS is also used for e-mail.
①Mail client installed

②Mailboxes are set to refer to Maildir

③Test sending mail
Send test mail to yourself [mail (user name)@(host name)].

Ctrl + D key to exit the main text

④Check incoming mail

2.4 Applied ClamAV to mail server Postfix

Set up Postfix and Clamav to work together to scan incoming and outgoing mail in real time.

①Install Amavisd and Clamav Daemon and start Clamav Daemon

If the server is not using a fully qualified domain name (FQDN) as the hostname, Amavis may fail to start. Also, since the OS hostname may change, set a valid hostname directly in the Amavis configuration file

②15-content_filter_mode edit

③Register your own domain name

④ edit

⑤ edit

Editorial content

⑥Settings reflect

⑦When you send an e-mail to yourself on Thuderbird, etc., if you see the following message in the header of the incoming e-mail, you have succeeded.

2.5 Applied spamassassin to mail server Postfix

2.5.1 Install spamassassin


②SpamAssassin Settings
The configuration file is "/etc/mail/spamassassin/".

  • Use default without additional settings
  • Creation of Maildir for storing spam mails
  • Create a directory in Maildir format to store spam emails
  • Create a directory ".Spam" in Maildir format for storing spam mails.
  • Creation is done by the target user.
2.5.2Procmail Preparation

①Install Procmail

If installed, the following results are returned

②Procmail Settings
If you put it in "/etc/procmailrc", which is in charge of the entire mail filter, it will be applied to all users.
The filter will be applied only to that user if it is written in "/home/username/.procmailrc", which is an individual mail filter file for each user.
This time, to apply to all users, we will write the following in "/etc/procmailrc".

procmailrc description (newly created)

2.5.3 Postfix Configuration

① Edit

②Reflecting and activating settings

2.5.4 Spam Email Learning

Allows all users to learn the entire contents of their ".Spam" directory as spam mail
①Spam Email Learning

②Normal mail learning

③Create a script and register it with Cron
Name the file "" and place it under /opt/script/.
After saving the script, give it executable access as "chmod 750". Contents

After is created, create a definition file directly under /lib/systemd/system. The name should end in .service, such as spam-learns.service.
Type is defined by simple
Contents of spam-learns.service

④Send a blank email to yourself in Thunderbird, etc., and if you see the following message in the header of the received email, you have succeeded.