Email to timeline user with multiple email addresses/acceptable domains

Had this come over a few times in support. Basically the idea is to have a single user with multiple acceptable domains. Sometimes the logged in user has an email that isn't actually the address they send through all the time. This request is to be able to associate multiple email addresses to one user in order to have multiple acceptable domains. While they can add the user with another address it is not a good experience to have to manage both bcc addresses.

In another case I have seen, a customer email address was actually forwarding through another email address due to a company domain name change. Thus when they view their ETT inbound email address it is showing the incorrect bcc address.

I'll also add that the workaround of adding a separate user is not really feasible as they won't have access to the drafts if they are logging in through another user.