Using Classic Outlook on Windows for personal email, calendar, and contact management
A follow-up. This seems to work very well from the desktop; I installed my bazillion emails and they all flow right to the same inbox, and I can reply as if from the correct address.
As an added bonus, this inbox automatically syncs with the Outlook app on my Android devices, from which I can read and delete the messages (pretty much like IMAP) from all email addresses without installing them individually on the device.
The two considerations I've found are these:
1. I think (but have not tested) that this approach will only deliver new messages to the Android device if the primary desktop with every email is on and regularly checking email.
2. The Android address can only respond from email addresses that are installed on it, so while you can read email from "@address2.com," you can only respond from "@outlook.com" unless you install the address2.com email on the device itself.