Let me go one step further and show you how I arrived at the answer. First things first, let's determine what is listening on port 443 or https.
sudo ss -ltpn |grep :443
Which gives the result of :
LISTEN 0 128 *:443 *:* users:(("apache2",pid=11612,fd=3),("apache2",pid=11611,fd=3),("apache2",pid=3437,fd=3))
Ahh... so apache is handling https traffic. All of apache's configs are kept under /etc/apache2. A quick look in the directory shows me a couple of config files and several sub directories.
apache2.conf has the base config + a quick explanation of the directory structure in the comments.
You have three directory categories and two statuses to choose from. You have conf, mods, and sites for categories and available and enabled for statuses.
So you see directories like conf-available and conf-enabled and so on. We are interested in what is actually enabled. IF we were looking for Sogo.my.domain that would be a virtual host and you would find that under sites-enabled. If we are looking for my.domain/sogo that is going to be under a configured directory which you will find in conf-enabled. Assuming we don't know which that is we just check each directory in turn looking for clues.
My sites-enabled has :
000-default.conf and default-ssl.conf. Neither of these had a reference to Sogo so it isn't a virtual host.
Next we check conf-enabled:
Surprise! there is a SOGo.conf. It is probably going to be SOGo but let's make sure by reading the conf file.
Inside we find
ProxyPass /SOGo http://127.0.0.1:20000/SOGo retry=0
so definitely it is going to be my.domain/SOGo/
Hopefully this helps!
I wrote this from a "assumes nothing" standpoint and I did not intend to give the impression I was talking down to you.
ETA: added sudo to the ss command to allow access to process application and pid information