$sudo apt install apache2 mariadb-server php-{xml,pear,imap,intl,common,json,curl,mbstring,mysql,gd,imagick,zip,opcache,sqlite3} libapache2-mod-php

$ sudo useradd -r -u 150 -g mail -d /var/vmail -s /sbin/nologin -c "Virtual Mail User" vmail

$ sudo mkdir -p /var/vmail

$ sudo chmod -R 770 /var/vmail

$ sudo chown -R vmail:mail /var/vmail

$ mysql -u root -p

MariaDB [(none)]> CREATE DATABASE postfixadmin;

MariaDB [(none)]> GRANT ALL PRIVILEGES ON postfixadmin.* TO 'postfixadmin'@'localhost' IDENTIFIED BY '5tr0n6p455w0rd';

MariaDB [(none)]> FLUSH PRIVILEGES;

MariaDB [(none)]> \q

$ sudo apt install postfix-mysql

$ sudo mkdir -p /etc/postfix/sql

$ sudo nano /etc/postfix/sql/mysql_virtual_alias_maps.cf

user = postfixadmin

password = 5tr0n6p455w0rd

hosts = localhost

dbname = postfixadmin

query = SELECT goto FROM alias WHERE address='%s' AND active = '1'

$ sudo nano /etc/postfix/sql/mysql_virtual_domains_maps.cf

user = postfixadmin

password = 5tr0n6p455w0rd

hosts = localhost

dbname = postfixadmin

query = SELECT domain FROM domain WHERE domain='%s' AND active = '1'

$ sudo nano /etc/postfix/sql/mysql_virtual_mailbox_maps.cf

user = postfixadmin

password = 5tr0n6p455w0rd

hosts = localhost

dbname = postfixadmin

query = SELECT maildir FROM mailbox WHERE username='%s' AND active = '1'

$ sudo nano /etc/postfix/sql/mysql_virtual_alias_domain_maps.cf

user = postfixadmin

password = 5tr0n6p455w0rd

hosts = localhost

dbname = postfixadmin

query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('%u', '@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

$ sudo nano /etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf

user = postfixadmin

password = 5tr0n6p455w0rd

hosts = localhost

dbname = postfixadmin

query = SELECT maildir FROM mailbox,alias_domain WHERE alias_domain.alias_domain = '%d' and mailbox.username = CONCAT('%u', '@', alias_domain.target_domain) AND mailbox.active = 1 AND alias_domain.active='1'

$ sudo nano /etc/postfix/sql/mysql_virtual_mailbox_limit_maps.cf

user = postfixadmin

password = 5tr0n6p455w0rd

hosts = localhost

dbname = postfixadmin

query = SELECT quota FROM mailbox WHERE username='%s' AND active = '1'

$ sudo nano /etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf

user = postfixadmin

password = 5tr0n6p455w0rd

hosts = localhost

dbname = postfixadmin

query = SELECT goto FROM alias,alias_domain WHERE alias_domain.alias_domain = '%d' and alias.address = CONCAT('@', alias_domain.target_domain) AND alias.active = 1 AND alias_domain.active='1'

$ sudo postconf -e "myhostname = $(hostname -f)"

UPD: нужно заменить $(hostname -f) на домен своей будущей почты, чтобы при настройке DKIM SFP и дальнейшей проверке не было проблем.

$ sudo postconf -e "mydestination = localhost"

$ sudo postconf -e "mynetworks = 127.0.0.0/8" 

ВАЖНО: вводить нужно свои подсети так как в противном случае сервер может стать ретранслятором спама, в следствии чего, домен окажется в спамбазах.

$ sudo postconf -e "inet_protocols = ipv4"

$ sudo postconf -e "inet_interfaces = all"

$ sudo postconf -e "smtpd_tls_cert_file = /etc/ssl/certs/ssl-cert-snakeoil.pem" 

$ sudo postconf -e "smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key"

Пути выше можно заменить на пути ваших сертификатов (купленных или созданных в Let's Encrypt)

$ sudo postconf -e "smtpd_tls_key_file = /etc/ssl/private/ssl-cert-snakeoil.key"

$ sudo postconf -e "smtpd_tls_auth_only = yes"

$ sudo postconf -e "smtpd_sasl_type = dovecot"

$ sudo postconf -e "smtpd_sasl_path = private/auth"

$ sudo postconf -e "smtpd_sasl_auth_enable = yes"

$ sudo postconf -e "smtpd_recipient_restrictions = permit_sasl_authenticated, permit_mynetworks, reject_unauth_destination"

$ sudo postconf -e "virtual_transport = lmtp:unix:private/dovecot-lmtp"

$ sudo postconf -e "virtual_mailbox_domains = proxy:mysql:/etc/postfix/sql/mysql_virtual_domains_maps.cf"

$ sudo postconf -e "virtual_alias_maps = proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_catchall_maps.cf"

$ sudo postconf -e "virtual_mailbox_maps = proxy:mysql:/etc/postfix/sql/mysql_virtual_mailbox_maps.cf, proxy:mysql:/etc/postfix/sql/mysql_virtual_alias_domain_mailbox_maps.cf"

$ sudo nano /etc/postfix/master.cf

smtp inet n - y - - smtpd

#smtp inet n - y - 1 postscreen

#smtpd pass - - y - - smtpd

#dnsblog unix - - y - 0 dnsblog

#tlsproxy unix - - y - 0 tlsproxy

submission inet n - y - - smtpd

  -o syslog_name=postfix/submission

  -o smtpd_tls_security_level=encrypt

  -o smtpd_sasl_auth_enable=yes

# -o smtpd_reject_unlisted_recipient=no

# -o smtpd_client_restrictions=$mua_client_restrictions

# -o smtpd_helo_restrictions=$mua_helo_restrictions

# -o smtpd_sender_restrictions=$mua_sender_restrictions

# -o smtpd_recipient_restrictions=

# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject

  -o smtpd_client_restrictions=permit_sasl_authenticated,reject

  -o milter_macro_daemon_name=ORIGINATING

smtps inet n - y - - smtpd

  -o syslog_name=postfix/smtps

# -o smtpd_tls_wrappermode=yes

  -o smtpd_sasl_auth_enable=yes

# -o smtpd_reject_unlisted_recipient=no

  -o smtpd_client_restrictions=permit_sasl_authenticated,reject

# -o smtpd_client_restrictions=$mua_client_restrictions

# -o smtpd_helo_restrictions=$mua_helo_restrictions

# -o smtpd_sender_restrictions=$mua_sender_restrictions

# -o smtpd_recipient_restrictions=

# -o smtpd_relay_restrictions=permit_sasl_authenticated,reject

-o milter_macro_daemon_name=ORIGINATING

$ sudo apt install dovecot-mysql dovecot-imapd dovecot-lmtpd

$ sudo nano /etc/dovecot/conf.d/10-auth.conf

auth_mechanisms = plain  >  auth_mechanisms = plain login

Комментируем и снимаем комментирование

#!include auth-system.conf.ext 

!include auth-sql.conf.ext

$ sudo nano /etc/dovecot/dovecot-sql.conf.ext

driver = mysql

connect = host=localhost dbname=postfixadmin user=postfixadmin password=5tr0n6p455w0rd

default_pass_scheme = MD5-CRYPT

password_query = SELECT username as user, password, '/var/vmail/%d/%n' as userdb_home, 'maildir:/var/vmail/%d/%n' as userdb_mail, 150 as userdb_uid, 8 as userdb_gid FROM mailbox WHERE username = '%u' AND active = '1'

user_query = SELECT '/var/vmail/%d/%u' as home, 'maildir:/var/vmail/%d/%u' as mail, 150 AS uid, 8 AS gid, concat('dirsize:storage=', quota) AS quota FROM mailbox WHERE username = '%u' AND active = '1'

$ sudo nano /etc/dovecot/conf.d/10-mail.conf

mail_location = maildir:/var/vmail/%d/%n

mail_uid = vmail

mail_gid = mail

mail_privileged_group = mail

first_valid_uid = 150

last_valid_uid = 150

$ sudo nano /etc/dovecot/conf.d/10-master.conf

service lmtp {

     unix_listener /var/spool/postfix/private/dovecot-lmtp {

     mode = 0600

     user = postfix

     group = postfix

     }

}

service auth {

     unix_listener /var/spool/postfix/private/auth {

     mode = 0666

     user = postfix

     group = postfix

}

unix_listener auth-userdb {

     mode = 0600

     user = vmail

}

user = dovecot

}

service auth-worker {

     user = vmail

}

$ sudo chown -R vmail:dovecot /etc/dovecot

$ sudo chmod -R o-rwx /etc/dovecot

$ sudo systemctl restart postfix dovecot

$ wget -q https://downloads.sourceforge.net/project/postfixadmin/postfixadmin/postfixadmin-${VERSION}/postfixadmin-${VERSION}.tar.gz

$ tar xzf postfixadmin-${VERSION}.tar.gz

$ sudo mv postfixadmin-${VERSION}/ /var/www/postfixadmin

$ rm -f postfixadmin-${VERSION}.tar.gz

$ mkdir /var/www/postfixadmin/templates_c

$ sudo chown -R www-data: /var/www/postfixadmin

$ sudo nano /var/www/postfixadmin/config.local.php

$CONF['database_type'] = 'mysqli';

$CONF['database_host'] = 'localhost';

$CONF['database_user'] = 'postfixadmin';

$CONF['database_password'] = '5tr0n6p455w0rd';

$CONF['database_name'] = 'postfixadmin';

$CONF['configured'] = true;

?>

$config['plugins'] = array();

$config['smtp_server'] = 'tls://localhost';

$config['smtp_user'] = '%u';

$config['smtp_pass'] = '%p';

$config['smtp_conn_options'] = [

  'ssl' => [

    'peer_name' => 'mail.example.com',

//    'cafile' => '/etc/ssl/certs/ca-certificates.crt'

  ],