Thanks @ecosenza for reaching out to me.
It´d be great to have that additional email addresses (plural) with full functionality thus association of inbound emails to a contact will work, no matter from which email that contact had sent an email to us.
Adding another contact per email address is consuming licensed contacts although it´s the same person. Not so nice… and truly not helping any HubSpot customer who for sure has the intention to have one comprehensive contact document for a person which contains all communication, web page visits, workflows …
Certainly a missing feature that should quickly rise high on the prio list since it has qualitative and commercial impact.