First off, create .env file from the .example.env and configure it appropriately. You'll need a MariaDB database, Discord bot token, and a domain for receiving mail.
The MariaDB database schema will be auto-generated by Sequelize upon starting the app. You'll need just an empty database and credentials to start off.
Koirameili runs its own mail server on port 25. You can point your domain to your server using A or MX (or anything else that works) record.
Install required npm dependencies using:
$ npm install
After configuring the .env file and installing dependencies, you can run the app using:
$ npm run
If you're testing by sending mail from a public online mail server, you'll realise that your server and DNS records must be accessible from the Internet in order to mails to deliver.
You can try to make everything local and send mails locally, but I prefer to do it the "hard" way. I used SSH remote port forwarding, but anything like router port forwarding or a tunnel server would work.
To use SSH remote port forwarding you'll need to enable GatewayPorts and AllowTcpForwarding in the /etc/ssh/sshd_config on your public server. To begin forwarding, just connect to your remote server using your local machine as follows:
$ ssh -R 25:localhost:25 you@yourserver.com
You can't usually send mail directly to an IP address, therefore you'll need to set up DNS record for it. For developement purposes, A record is quick and easy to set up. Just point your domain to your server and you'll be able to send emails to mailbox@yourserver.com.