There is no excuse for Notes not handling multiple email accounts in a unified inbox.
I was filling out the g2.com survey as requested by someone in HCL, and the very first comparative question it asks to rate the software is "Unified Inbox: Consolidates multiple email accounts into one viewable platform". On this HCL Notes fails miserably and horribly. Not only does it not allow consolidating inboxes from other mail platforms or multiple Domino domains, it doesn't even allow consolidating multiple email accounts within the same mail system. This is a gross deficiency. If you want people to use your product, make it a personal productivity tool. No one has only one email account.