Pre-requisites

There are some things you'll need to do before you can install Postal.

Servers

We strongly recommend installing Postal on its own dedicated server (i.e. a server running no other software). The minimum specification for Postal is as follows:

• At least 4GB of RAM
• At least 2 CPU cores
• An appropriate amount of disk space (at least 25GB) for your use case

Most people install Postal on virtual servers. There are lots of providers to choose from including Digital Ocean and Linode.

One thing to be aware of is you'll need to ensure that your provider does not block port 25 outbound. This is quite common and is used to prevent abuse from spammers.

It doesn't matter what operating system you choose as long as you are able to install Docker on it (see next section). Nothing in these instructions will make assumptions about your operating system.

Docker

Postal runs entirely using containers which means to run Postal you'll need some software to run these containers. We recommend using Docker for this purpose but you can use whatever software you wish.

You'll need to install Docker Engine on your server to begin with. Follow the instructions on the Docker website to install Docker.

You'll also need to ensure you have the Docker Compose plugin installed.

Before continuing ensure that you can run both docker and docker compose from your prompt.

System utilities

There are a few system utilities that you need to have installed before you'll be able to run some of the Postal commands.

On Ubuntu/Debian:

apt install git curl jq

On CentOS/RHEL:

yum install git curl jq

Git & installation helper repository

You'll need to make sure you have git installed on your server. You'll then need to clone the Postal installation helper repository. This contains some bootstrapping config and other useful things which will speed along your installation.

git clone https://github.com/postalserver/install /opt/postal/install
sudo ln -s /opt/postal/install/bin/postal /usr/bin/postal

MariaDB (10.6 or higher)

Postal requires a database engine to store all email and other essential configuration data. You will need to provide credentials that allow full access to create and delete databases as well as having full access to any databases created. Postal will provision a database automatically for each mail server that you create.

We do not support using MySQL in place of MariaDB.

You can run MariaDB in a container, assuming you have Docker, using this command:

docker run -d \
   --name postal-mariadb \
   -p 127.0.0.1:3306:3306 \
   --restart always \
   -e MARIADB_DATABASE=postal \
   -e MARIADB_ROOT_PASSWORD=postal \
   mariadb

• This will run a MariaDB instance and have it listen on port 3306.
• Be sure to choose a secure password. You'll need to put this in your Postal configuration when you install it so be sure to make a (secure) note of it.
• If you are unable or unwilling to grant root access, the database user you create separately needs all permissions on databases called postal and postal-* (this prefix can be configured in the message_db part of your configuration).