Most of us have multiple email accounts, but you can only use Google Now with one of them at a time. If yours is a personal account, forward important work emails, like appointments, reminders and due dates, to your personal email so you can benefit from Google Now’s personal assistant features.
You can use Gmail’s filters to forward your work emails by subject, sender or keyword. That way you won’t forward anything unnecessary. Then, create another filter to keep your work messages from cluttering your inbox. Google Now will treat those forwarded and filtered emails just like any other: serving up reminders, location features, and other special cards whenever you need them.
How to: Forward email to your main Gmail account so Google Now sees it [Android Central]