[keycloak-user] Customize email "from" by FQDN inside the same realm

Hello, We are providing a single web application that is accessed under several domain names. We want to use KC to do the authentication to this web app. With the different domains names also come different "brandings" or "themes" for each domain. As we have a single realm, we managed to do this branding using a dedicated service that map KC templates' assets (css, img, ...) to the right file, based on the FQDN. One points remains hard to change: the "from" and "reply to" fields in every mail KC sends (like password recovery). These fields are statically configured for the whole realm in the Email settings and I don't think there exists any way to make this "dynamic". So I turn to you folk to grab some hints/ideas about ways I could modify KC in order to replace the email' "sender" by another value using the request's domain. I never dug into KC code yet so I don't have any clue where to start acually. Many thanks, Nicolas GILLET