Instalación de servidor Postfix y Mysql

Requisitos previos:

Contar con un servidor LAMP previamente instalado y configurado, FQDN configurado y Mysql instalado y configurado.

Paso 1: Instalar los paquetes necesarios

user@server:$sudo apt-get install postfix postfix-mysql dovecot-core dovecot-imapd dovecot-pop3d dovecot-lmtpd dovecot-mysql

Paso 2: Crear la base de datos, tabla de dominios, usuarios y alias

mysqladmin -p create servermail
mysql -u root -p
mysql > GRANT SELECT ON servermail.* TO 'usermail'@'127.0.0.1' IDENTIFIED BY 'mailpassword';
mysql > FLUSH PRIVILEGES;
mysql> USE servermail;

CREATE TABLE `virtual_domains` (
`id`  INT NOT NULL AUTO_INCREMENT,
`name` VARCHAR(50) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `virtual_users` (
`id` INT NOT NULL AUTO_INCREMENT,
`domain_id` INT NOT NULL,
`password` VARCHAR(106) NOT NULL,
`email` VARCHAR(120) NOT NULL,
PRIMARY KEY (`id`),
UNIQUE KEY `email` (`email`),
FOREIGN KEY (domain_id) REFERENCES virtual_domains(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE TABLE `virtual_aliases` (
`id` INT NOT NULL AUTO_INCREMENT,
`domain_id` INT NOT NULL,
`source` varchar(100) NOT NULL,
`destination` varchar(100) NOT NULL,
PRIMARY KEY (`id`),
FOREIGN KEY (domain_id) REFERENCES virtual_domains(id) ON DELETE CASCADE
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

INSERT INTO `servermail`.`virtual_domains`
(`id` ,`name`)
VALUES
('1', 'example.com'),
('2', 'hostname.example.com');

INSERT INTO `servermail`.`virtual_users`
(`id`, `domain_id`, `password` , `email`)
VALUES
('1', '1', ENCRYPT('firstpassword', CONCAT('$6$', SUBSTRING(SHA(RAND()), -16))), 'email1@example.com'),
('2', '1', ENCRYPT('secondpassword', CONCAT('$6$', SUBSTRING(SHA(RAND()), -16))), 'email2@example.com');

INSERT INTO `servermail`.`virtual_aliases`
(`id`, `domain_id`, `source`, `destination`)
VALUES
('1', '1', 'alias@example.com', 'email1@example.com');

mysql > exit

Paso 3: Configuración de Postfix main.cf

Hasta el momento se ha tomado como referencia la guía publicada en digital ocean https://www.digitalocean.com/community/tutorials/how-to-configure-a-mail-server-using-postfix-dovecot-mysql-and-spamassassin, pero esta guía esta pensada para una versión de ubuntu muy antigua y no funciona en las versiones modernas, es por ello que le hice adaptaciones y el siguiente codigo del archivo de configuración es fruto de revisar muchos post y de aplicar el criterio sumado a varias pruebas de ensayo error. El código siguiente ha sido probado en ubuntu 16.04 y funciona a la perfección.

cp /etc/postfix/main.cf /etc/postfix/main.cf.orig
nano /etc/postfix/main.cf

# See /usr/share/postfix/main.cf.dist for a commented, more complete version


# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# TLS parameters
#smtpd_tls_cert_file=/etc/ssl/certs/ssl-cert-snakeoil.pem
#smtpd_tls_key_file=/etc/ssl/private/ssl-cert-snakeoil.key
#smtpd_use_tls=yes
#smtpd_tls_session_cache_database = btree:${data_directory}/smtpd_scache
#smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache

#agregar estas dos lineas
smtpd_tls_security_level = may
smtp_tls_security_level = may

#smtpd_tls_cert_file=/etc/dovecot/dovecot.pem
#smtpd_tls_key_file=/etc/dovecot/private/dovecot.pem

smtpd_tls_cert_file = /etc/letsencrypt/live/enappserver.com/cert.pem
smtpd_tls_key_file = /etc/letsencrypt/live/enappserver.com/privkey.pem
smtpd_tls_CAfile = /etc/letsencrypt/live/enappserver.com/chain.pem

smtpd_use_tls=yes
#smtp_use_tls = yes
smtpd_tls_auth_only = yes
smtp_tls_note_starttls_offer = yes

#agregar otras 2 lineas
smtpd_tls_received_header = yes
smtpd_tls_loglevel = 1

smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_auth_enable = yes
smtpd_sasl_local_domain =
broken_sasl_auth_clients = yes
smtpd_recipient_restrictions =
        permit_sasl_authenticated,
        permit_mynetworks,
        reject_unauth_destination

# See /usr/share/doc/postfix/TLS_README.gz in the postfix-doc package for
# information on enabling SSL in the smtp client.

#smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = mail.enappserver.com
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailbox_size_limit = 0
message_size_limit = 0
virtual_mailbox_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
strict_mailbox_ownership = no

virtual_transport = lmtp:unix:private/dovecot-lmtp

virtual_mailbox_domains = mysql:/etc/postfix/mysql-virtual-mailbox-domains.cf
virtual_mailbox_maps = mysql:/etc/postfix/mysql-virtual-mailbox-maps.cf
virtual_alias_maps = mysql:/etc/postfix/mysql-virtual-alias-maps.cf

#OpenDKIM
milter_default_action = accept
milter_protocol = 2
smtpd_milters = inet:localhost:8891
#smtpd_milters = inet:8891@localhost
non_smtpd_milters = inet:localhost:8891

#controlar el reintento de correos no enviados
maximal_queue_lifetime = 3h
queue_run_delay = 300s
minimal_backoff_time = 300s
maximal_backoff_time = 4000s

Lo siguiente es crear y configurar los archivos necesarios para conectar postfix con la base de datos mysql y las tablas ya creadas

nano /etc/postfix/mysql-virtual-mailbox-domains.cf
		
user = usermail
password = mailpassword
hosts = 127.0.0.1
dbname = servermail
query = SELECT 1 FROM virtual_domains WHERE name='%s'

nano /etc/postfix/mysql-virtual-mailbox-maps.cf 
		
user = usermail
password = mailpassword
hosts = 127.0.0.1
dbname = servermail
query = SELECT 1 FROM virtual_users WHERE email='%s'

nano /etc/postfix/mysql-virtual-alias-maps.cf
		
user = usermail
password = mailpassword
hosts = 127.0.0.1
dbname = servermail
query = SELECT destination FROM virtual_aliases WHERE source='%s'

Finalmente reiniciamos el servicio de postfix y probamos la configuracion de los tres archivos. Deberíamos obtener un 1 en cada caso.

service postfix restart

postmap -q example.com mysql:/etc/postfix/mysql-virtual-mailbox-domains.cf
postmap -q email1@example.com mysql:/etc/postfix/mysql-virtual-mailbox-maps.cf
postmap -q alias@example.com mysql:/etc/postfix/mysql-virtual-alias-maps.cf

Copiamos el archivo de configuracion master.cf
   cp /etc/postfix/master.cf /etc/postfix/master.cf.orig
Editamos el  archivo master.cf
   nano /etc/postfix/master.cf

El código debería quedar así:

smtp      inet  n       -       -       -       -       smtpd
submission inet n       -       -       -       -       smtpd
  -o syslog_name=postfix/submission
smtps     inet  n       -       -       -       -       smtpd
  -o syslog_name=postfix/smtps
  -o smtpd_tls_wrappermode=yes
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
  -o milter_macro_daemon_name=ORIGINATING
  -o smtpd_tls_security_level=encrypt
  -o smtpd_relay_restrictions=permit_mynetworks,permit_sasl_authenticate,reject
  -o smtpd_client_restrictions=
  -o smtpd_helo_restrictions=
  -o smtpd_sender_restrictions=
  -o smtpd_recipient_restrictions=
  -o smtpd_data_restrictions=
  -o smtpd_end_of_data_restrictions=

pickup    unix  n       -       -       60      1       pickup
cleanup   unix  n       -       -       -       0       cleanup
qmgr      unix  n       -       n       300     1       qmgr
tlsmgr    unix  -       -       -       1000?   1       tlsmgr
rewrite   unix  -       -       -       -       -       trivial-rewrite
bounce    unix  -       -       -       -       0       bounce
defer     unix  -       -       -       -       0       bounce
trace     unix  -       -       -       -       0       bounce
verify    unix  -       -       -       -       1       verify
flush     unix  n       -       -       1000?   0       flush
proxymap  unix  -       -       n       -       -       proxymap
proxywrite unix -       -       n       -       1       proxymap
smtp      unix  -       -       -       -       -       smtp
relay     unix  -       -       -       -       -       smtp
showq     unix  n       -       -       -       -       showq
error     unix  -       -       -       -       -       error
retry     unix  -       -       -       -       -       error
discard   unix  -       -       -       -       -       discard
local     unix  -       n       n       -       -       local
virtual   unix  -       n       n       -       -       virtual
lmtp      unix  -       -       -       -       -       lmtp
anvil     unix  -       -       -       -       1       anvil
scache    unix  -       -       -       -       1       scache
maildrop  unix  -       n       n       -       -       pipe
  flags=DRhu user=vmail argv=/usr/bin/maildrop -d ${recipient}
${user}
${user}
uucp      unix  -       n       n       -       -       pipe
  flags=Fqhu user=uucp argv=uux -r -n -z -a$sender - $nexthop!rmail ($recipient)
ifmail    unix  -       n       n       -       -       pipe
  flags=F user=ftn argv=/usr/lib/ifmail/ifmail -r $nexthop ($recipient)
bsmtp     unix  -       n       n       -       -       pipe
  flags=Fq. user=bsmtp argv=/usr/lib/bsmtp/bsmtp -t$nexthop -f$sender $recipient
scalemail-backend unix  -       n       n       -       2       pipe
  flags=R user=scalemail argv=/usr/lib/scalemail/bin/scalemail-store ${nexthop} $$
mailman   unix  -       n       n       -       -       pipe
  flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
  ${nexthop} ${user}