Domino will know the old and new aliases of email address and remove the old email address in the CC/To Field when replying back. More details are provided below.
Remove Duplicate E-mails of same E-Mail Chain where aliases were used: This is a feature I see in other modern E-Mail systems like GMail or Outlook. If I sent an E-Mail to a GMail account and its alias, that Gmail inbox would only see 1 E-mail in the inbox for that E-Mail Chain.
Remove Aliases Reply-To-All messages: It would be nice to include the Domain Aliases (from "Domains" document in names.nsf) and also from the Person Document in the Location Document in the Notes Client to know to remove its Aliases from the E-Mail Chain.