Requisitos previos:
El presente manual fue desarrollado para la distribución Debian 7.
Asegurarse que se tiene configurado el servidor, y que el mismo esta actualizado y listo para poder instalar
paquetes del repositorio.
Considere que se efectuarán algunos de los pasos que se indican en el manual original.

Contenido:

1. Change The Default Shell.
2. Synchronize the System Clock.
3. Install Postfix, Dovecot, MySQL, phpMyAdmin, rkhunter, binutils. 
4. Activando el servicio al inicio.

1. Change The Default Shell.

/bin/sh is a symlink to /bin/dash, however we need /bin/bash, not /bin/dash. Therefore we do this:

dpkg-reconfigure dash

Use dash as the default system shell (/bin/sh)? ← no

If you don't do this, the ISPConfig installation will fail.

2. Synchronize the System Clock.

Como es un contenedor para establecer el uso horario y demás empleamos el siguiente comando:

dpkg-reconfigure tzdata

3. Install Postfix, Dovecot, MySQL, phpMyAdmin, rkhunter, binutils.

We can install Postfix, Dovecot, MySQL, rkhunter, and binutils with a single command:

apt-get install postfix postfix-mysql postfix-doc mysql-client mysql-server openssl getmail4 rkhunter 
binutils dovecot-imapd dovecot-pop3d dovecot-mysql dovecot-sieve sudo

You will be asked the following questions:

General type of mail configuration: ←- Internet Site

System mail name: ←- server1.example.com

New password for the MySQL “root” user: ←- yourrootsqlpassword

Repeat password for the MySQL “root” user: ←- yourrootsqlpassword

Now edit the following file:

nano /etc/postfix/master.cf

Uncomment the submission and smtps sections as follows (leave -o milter_macro_daemon_name=ORIGINATING as we don't need it):

[...]
submission inet n       -       -       -       -       smtpd
  -o syslog_name=postfix/submission
  -o smtpd_tls_security_level=encrypt
  -o smtpd_sasl_auth_enable=yes
  -o smtpd_client_restrictions=permit_sasl_authenticated,reject
#  -o milter_macro_daemon_name=ORIGINATING
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
[...]

Restart Postfix afterwards:

/etc/init.d/postfix restart

We want MySQL to listen on all interfaces, not just localhost, therefore we edit /etc/mysql/my.cnf and comment out the line bind-address = 127.0.0.1:

nano /etc/mysql/my.cnf

  [...]
  # Instead of skip-networking the default is now to listen only on
  # localhost which is more compatible and is not less secure.
  #bind-address           = 127.0.0.1
  [...]

Tomado de: https://www.howtoforge.com/perfect-server-debian-wheezy-apache2-bind-dovecot-ispconfig-3