I want to know if there is any chance to lose the emails if I want to instal wordpress on a virtualmin where is allready a website made in Html. I just want to install wordpress but this is my first time using Virtualmin so I don’t know the rules, and I want to be sure that the email are safe.
There is zero risk of loss of email if you install WordPress.
You could install WordPress via Virtualmin’s Installed Scripts option - this is a one-click type install - or you could do it the old-fashioned way - upload the compressed file, uncompress it and then invoke the install by visiting the URL. In either case, there is zero risk of anything else blowing up.