oauth: use alternate field for email address?

Hello! We would like to configure mailcow to allow our keycloak users to sign in to it. Unfortunately, some of our users already have email addresses configured in keycloak. For these users at least, they they are unable to sign in to mailcow with the vague error message “Could not create mailbox on login”. Digging into the source code, that message seems to come from this part of functions.auth.inc.php

which seems to be attempting to parse the OIDC email value into a local part and domain. Is it possible to send these values as separate fields, like we already have to do for mailcow_template?

I should probably mention that I’ve been trying to work around this on the keycloak side too, but to no avail. It doesn’t seem like there’s a way to override an attribute with a value that is not already stored exactly in keycloak. So we could send just the localpart, for example, by mapping email to username, but there doesn’t seem to be a way to map email to username + @domain