Mail Server

https://mailinabox.email/
http://www.postfix.org/


http://aurellem.org/free/html/email.html
https://arstechnica.com/information-technology/2014/02/how-to-run-your-own-e-mail-server-with-your-own-domain-part-1/
https://www.digitalocean.com/community/tutorials/how-to-run-your-own-mail-server-with-mail-in-a-box-on-ubuntu-14-04