Virtualmin create a catch-all email account

This tutorial will cover how to setup a catch-all email account. Once finished, it will be the default destination for any email arriving at your domain, unless overridden by another email account or alias.

It assumes you have logged into Virtualmin as the root user.

You can make any email account the default (or catch-all) account for a given domain.

1. Choose the domain for which you would like to setup a catch-all address. You can do that by selecting the domain name from the drop-down box on the top-left.
2. Click Edit Users.
3. Click the name of the email account you would like to make a catch-all account.
4. Click Email Settings.
5. In Additional email addresses, type @example.com, where example.com is the name of your domain name.
6. Click Save, and this account will now be the default email address for this domain.

Src:
https://www.virtualmin.com/documentation/tutorial/how-to-create-a-catch-all-email-account/