https://github.com/acmephp/core
https://github.com/fbett/le-acme2-php
https://github.com/skoerfgen/ACMECert
https://stackoverflow.com/questions/23713295/configure-catch-all-alias-in-postfix-using-mysql
https://legacy.thomas-leister.de/postfix-catch-fuer-nicht-existierende-postfaecher/
https://www.lunanode.com/guides/postfix_smtp_secure
https://stackoverflow.com/questions/19970938/postfix-and-save-to-sent-mail-dir
https://serverfault.com/questions/331981/where-to-set-catch-all-address-in-postfix-virtual-mailboxes-in-affect
https://serverfault.com/questions/63518/how-can-i-forward-mail-while-saving-a-copy-using-postfix-and-mysql
https://superuser.com/questions/721917/mixing-virtual-forwards-and-virtual-mailboxes-in-postfix
https://workaround.org/ispmail/jessie/postfix-mysql
https://www.admin-magazin.de/Das-Heft/2012/02/Eigener-Mailserver-mit-Postfix-und-Dovecot
https://123qwe.com/
https://thomas-leister.de/mailserver-debian-stretch/
https://klingt.net/blog/my-netcup-server-with-arch-linux-docker-and-caddy/

Gitlab -> gitlab.com
Gogs -> gogs.io

Postfix Multi-Domain-SSL:
    http://postfix.1071664.n5.nabble.com/How-to-use-the-new-server-TLS-SNI-feature-3-4-x-td100786.html#a101029