Throughout our Free and Open Source Software tutorials, we need to specify passwords for things. Creating random passwords is surprisingly hard, but we've found a method that's very serviceable and makes it easy to do as we all should: ensure every separate identity or service has a strong password that is unique to that identity and application (i.e. never use the same password in more than one place). We also strongly encourage you all to track your passwords using a password manager!
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.