Two considerations here:
1) There are tons of apps in the Play store that will sync Exchange Server (Outlook email).
2) Even though the email may be on your own personal cellphone, it belongs to the company (data is a commodity now). So if they decide to wipe your phone when you quit or get let go, you have no way to stop them from doing it.
We're still in the "BYOD (bring your own device to work) is a gray area, legally" era. I wouldn't mix business and a cellphone I paid for until the courts have shown which way the wind is going to blow. (And I don't think it's going to blow the way we'd like it to.)