Gmail integrations just don't work with some accounts and will never work with the primary account. Email integration will ignore some forwards/catch-all accepted emails but work fine with others. It seems awfully flakey.
I have an entire GApps domain that I can't even turn Now on for, and I have no idea why.
Edit: Ahh the standard HN, "someone said something about Google that isn't glowing" flag instinct. Sorry that my experience with Now has been negative and you don't like that, flag away. Amusingly, the video comment (id=8493719) was flagged down into the negatives rather quickly, partially recovered and is continually being flagged.
It's mostly just a hypothetical, I don't expect anyone to have the answer (Google won't even officially acknowledge that Now integration is broken in GApps).
It is mostly annoying that Google introduces new features that they apparently don't care about making work for their paying customers.