I need a best practice suggestions related to my FQDN for my server that's also the Postfix $mydestination

So I have a few URL's of my own. Let's call AllSites.com my main one that I named my Ubuntu 16.04 server with. After getting Virtualmin up and running on the AllSites server do I immediately create a new virtual server for AllSites.com?
That seems wrong to me because admin@allsites.com isn't a virtual mail account, it's a real Unix account. My instinct is to make a default server in Apache for HTTP and HTTPS which represents any outside request for AllSites.com.