How To Setup Mail Server Using Postfix Dovecot with SSL Certificate on Ubuntu 18.04 LTS

I want to send and receive mail with this server from my Window Mail client, how can I do so?

and how to send mail with that

I am just learning how to set up my own email server. I am confused on ssl/tsl is verified. Lots of blogs and tutorials say you need to get an ssl/tsl cert so your email server is not blacked listed. On your openssl is that a self-signed ssl/tsl cert? Do I have buy one for like $100 a year?

No use courier-imaps and pop3s?
Request use courier ssl/tls