URL for webmail redirect
By default, Virtualmin will redirect requests to http://webmail.thedomain.com to Usermin on the same system, like https://thedomain.com:20000/. However, this field can be used to change the redirect URL, perhaps to a single hostname for all your domains for which you have an SSL certificate, like https://webmail.yourcompany.com:20000/. Or you can redirect to another webmail application on the same domain, by entering a URL like http://www.${DOM}/squirrelmail/.