1.5 Creating Postfix User Accounts and Groups

Postfix requires that some special user accounts and groups be created prior to installation. 

First create a user account "postfix" with a user id and group id that are unique (ie not used by any other user account). Ideally this should also be an account that no-one can log into. The account does not need an executable login shell or a home directory that exists. Entries can be added using the /usr/sbin/adduser and /usr/sbin/addgroup command line tools.

Typical  /etc/password and /etc/group file entries look  like this. 

/etc/passwd:
postfix:*:6789:6789:/no/where:/no/shell

/etc/group:
postfix:*:6789:

Next, create a group called "postdrop" with a group id that is not used by any other user account. Not even by the postfix user account. A typical /etc/group entry looks like:

postdrop:*:9876:

1.6 Installing Postfix

It is recommended that you download the latest version of Postfix and install it on your system. Most Linux distributions include Postfix but this is sometimes not imstalled by defaults and may well not be the latest release.

The very latest Postfix release can be downloaded from:

 https://www.postfix.org/download.html

 Once download unpack the archive and build it using the “make” command:

                make

 After the build is complete the package must be installed. Installation must be performed as super user and can be achieved using make as follows:

               make install

The installation process will ask a number of questions. Most of these questions have default responses and in all cases it should be safe to accept the default:

install_root: / 

tempdir: [/mydir/postfix-2.2.5] (usually directory where you
installed the sources)
config_directory: /etc/postfix 
daemon_directory: /usr/libexec/postfix 
command_directory: /usr/sbin 
queue_directory: /var/spool/postfix 
sendmail_path: /usr/sbin/sendmail 
newaliases_path: /usr/bin/newaliases 
mailq_path: /usr/bin/mailq 
mail_owner: postfix 
setgid_group: postdrop 
html_directory: no
manpage_directory: /usr/local/man
readme_directory: no 

Having answered the questions make will install Postfix on your system and you are ready to configure it.