I use gmail primarily. You can configure gmail to retrieve any of your POP3 accounts automatically.
If you are needing Exchange you can use the integrated Corporate Sync account. This is a pretty basic no frills client. As mentioned by lsmunos, Touchdown offers many features for Exchange accounts. Get the free trial first and see if you like it. I personally don't like it but then again my corporate account is not my primary and I only use it to manage an Exchange server for testing purposes.