Enable create proxy

[d-vo]

As mentioned in EasyEngine/site-command#252, I have the following problem. The feature request repo might be the more appropriate place.

I planned to install mailu as a mail solution on my server. By default, it listens on every IP address on port 80 and 443 which conflicts with the nginx-proxy server. I am looking for the most non-intrusive to forward the traffic from mail.mydomain.tld to the nginx running the mailu frontend.

I assume the most forward way is to let mailu listen on different ports (e.g. 8080 and 8443) and forward all traffic using the nginx-proxy to the docker container. I noticed that easy engine uses https://github.com/jwilder/nginx-proxy for the docker based nginx-proxy. I tried adding the "VIRTUAL_HOST" to the mailu docker files with no success...

A simple command enabling the traffic forwarding to other docker containers would be very much appreciated. Or any thoughts on an easy way to achieve this...