Customize direct-delivery Postfix configuration

Howdy folks,

I’ve just completed a domain migration (per Change the domain name or rename your Discourse ) which went just fine. However, I’m using the mail-receiver container with MX records for incoming mail to a couple of categories…..

As far as I can see the default configuation of the container hardcodes both the incoming domain and the path to the LetsEncrypt certs. Is it possible to allow two domains, either in the config, or via these advanced options?