After installing Mail-in-a-Box I was no longer able to SSH into my server as the firewall was blocking the port.
Thankfully I’m using DigitalOcean and was able to use their virtual console to SSH into the server and sudo ufw allow 1330; reload ssh to reopen the port.
So if you are using a custom port to connect with SSH, make sure you open up the port after installing Mail-in-a-Box before you exit the session and close the terminal.
The first thing I always do when spinning up a new droplet is to add a bit of security to the box:
adduser ubuntu
usermod -a -G www-data ubuntu
vi /etc/sudoers
ubuntu ALL=(ALL:ALL) ALL
vi /etc/ssh/sshd_config
Port 1330
PermitRootLogin no
PasswordAuthentication no
UseDNS no
reload ssh