Virtualmin does not automatically create a catch-all email address in the way that cPanel or other control panels will configure this user. On Virtualmin, you will need to create a user and assign it catch-all properties.

To create a catch-all email address (an email address that will accept all email sent to it if the address does not exist), follow these steps.

1. Login to Virtualmin as the root user or the main virtual server user. Switch to the virtual server with the domain you want to create a catch-all email on.
2. On the side menu, click on Edit Users and then in the main pane, click on the user you would like to be the catch-all user.
   
3. Expand Email Settings and in "Additional Email Addresses", enter @example.com on a empty line. Replace @example.com with your domain name. Click on Save.