Postfix is Wietse Venema's mailer that started life as an alternative to the
widely-used Sendmail program. It attempts to be fast, easy to administer, and
secure, while at the same time, being sendmail compatible enough to not upset
existing users. Thus, the outside has a sendmail-ish flavor, but the inside is
completely different.

This script builds postfix with optional support for Dovecot SASL, Cyrus SASL
can be enabled with:

  SASL=cyrus ./postfix.SlackBuild

You can also enable support for MySQL:

  DATABASE=mysql ./postfix.SlackBuild

PostgreSQL support can be enabled with:

  DATABASE=pgsql ./postfix.SlackBuild

On systems with multiple instances, add major version, eg: DATABASE=pgsql-9.5

This script will find support for BerkleyDB and PCRE automagically; TLS support
requires openssl package, openssl-solibs alone is not enough. Additionally, this
script doesn't add postfix user and groups, instead it offers sane defaults that
won't conflict with system users and groups, and other scripts from the SBo.

Package created with this script will conflict with stock sendmail package, you
*should* remove sendmail before installing postfix, otherwise sendmail updates
could break your postfix instance.

When upgrading from an older postfix version, make sure the variables such as
html_directory and readme_directory in /etc/postfix/main.cf point to the new
location. These can also be fixed later, afterwards make sure to run:

  postfix set-permissions

Furthermore, many of the utilities in postfix have multiple manpages such as
postconf(5) and postconf(8). Use man -k to find them, and don't forget to
subscribe to the postfix-users mailing list!