====== Postfix ======

===== Intro =====

Some notes regarding the installation & configuration of postfix in the most secure way I know so far today.

The target operating system is an Ubuntu 16.

===== Install =====


<code>
sudo apt-get install postfix 
sudo apt-get install mailutils
</code>

==== Config ====

Copy the default config:

<code>
cp /usr/share/postfix/main.cf.debian /etc/postfix/main.cf
</code>

This is my configuration for a host that it is isolated in internet, and 
it has no special needs (it is not the mail server for any domain, it only 
needs to send some emails): 

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


mail_owner = postfix

# 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.
myhostname = cloud.mister-i.com

mydomain = mister-i.com

myorigin = $myhostname

mydestination = $myhostname, localhost, novaprime

mynetworks_style = host

relay_domains = $mydestination

smtp_generic_maps = hash:/etc/postfix/generic

smtpd_banner = $myhostname ESMTP $mail_name
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
compatibility_level = 2

inet_interfaces = all
inet_protocols = all

smtpd_use_tls = no
smtp_use_tls = no 


</code>


It's very important to configure the file ''/etc/postfix/generic'' with a remapping of the local 
users to complete email addresses: 

<code>
# REMEMBER!!!! After making changes to this file you must run: 
#
# postmap /etc/postfix/generic
#
#

username   username@complete.server.address.com
</code>

In that way, every outgoing email is rewrited from username@localhost to username@complete.server.address.com and nowadays email servers can recognize it as a valid email 
address. 

After that **don't forget to run postmap /etc/postfix/generic** in order to update the database with the fresh configuration.

==== Open firewall ====


<code>
ufw allow 25
</code>

http://serverfault.com/questions/149903/what-ports-to-open-for-mail-server

==== Do some testing ====


<code>
mail --subject="hello from server" destination-address@example.com
</code>