18.04

Just about any and every server needs to be able to send email - whether it's end-user-email, like password recovery services for a website to emails to system administrators reporting on the status of system backups and errors. The problem is that it's non trivial (understatement) to set up a mail server properly.

SkFor any website that requires anyone (users or even just a few admins) to transfer secrets to and from it, you want to ensure the data is end-to-end encrypted. Today various browsers (like Firefox) give warnings when you're sending secret data (like passwords) "in the clear", namely unencrypted.

Update 2023-06-14: Here's a new tutorial for Ubuntu 22.04! Consider this older tutorial obsolete (but possibly helpful for people with older systems?)