Hide hostname from email metadata

I have trouble with email sent from keycloak. It exposes environment details about system in email metadata by sending hostname of k8s pod in Message-ID and Recieved: from helo part.

Received: from [IP]
Message-ID: <1234123123.432.123123123123123@example-deployment-0.keycloak-example-master-statefulset.default.svc.cluster.local>

Our keycloak is running on k8s and the hostname that is being used by keycloak is the hostname of k8s pod (“web-{0…N-1}.keycloak.default.svc.cluster.local”). Is there a way to hide this information in metadata?
Found similar issue on keycloak board [KEYCLOAK-14958] Cannot configure hostname / FQDN being used for outgoing email / SMTP - Red Hat Issue Tracker
Tried multiple solutions from k8s side and keycloak, but none of them worked.