I'll live with the alias. Default Gmail address doesn't appear to work.
I managed to get exactly one burst of emails from Phabricator after adding two additional emails and mashing the "Verify" button several hundred times. Not sure what is going on.
I then removed my original email, and re-added it, hoping to get the email verification sent and thus unclog my email issue. However, Phabricator refuses to send the verification email to that email.
So the non-Gmail address apparently verifies. I did manage to get a Gmail alias (appending the +foobar to the end of the address side) to work, and is currently set, but damned if I get notifications.