If you add/remove server IPs the file `/etc/apache2/sites-available/ispconfig.conf` gets recreated and it is missing the alias for Let's Encrypt ACME challenges. Copying over the current install template fixes that. 

Maybe one could remove this template duplication completely by using `server/conf/apache_ispconfig.conf.master` in the install process?

The `Header set Content-Type "text/plain"` was only in `server/conf/apache_ispconfig.conf.master` and not in `install/tpl/apache_ispconfig.conf.master` – is it necessary?

The cipher suites are only set now for ISPConfig's own vhost, the intermediate security profile from Mozilla is used here.

Do not move files to junk when autoresponder is on, just dont send an autoresponse when mail is marked as spam.

Improved permission settings for the /var/run/hhvm directory. Run Tools > Resync to force an update of existing HHVM starter scripts to apply this fix if you currently use HHVM.

Changed apache mod_proxy_fcgi configuration in vhost.conf.master from ProxyPassMatch to SetHandler so we can wrap the config directive it into <Directory ...> to avoid side affects with globally installed applications like phpmyadmin and roundcube.

ISPConfig itself does not read nor interpret this header, but there might be other
server components like PHP that might interact with it so I'll disable it just to be sure.

After enabling "Rewrite HTTP to HTTPS" and "Lets Encrypt SSL" the RewriteCond and RewriteRule got on the same line, becourse of an failing newline

Set default env[PATH] and env[HOSTNAME] since it is cleared by default setting clear_env = yes in php-fpm

Replace fastcgi_pass unix:/var/run/php5-fpm.sock; with fastcgi_pass unix:{fpm_socket}; in phpmyadmin and squirrelmail blocks, as they are considered apps and should use the same (apps.sock) listener.