In AppStore and Google Store you can find Mobile OWA for your mobile devices.
Mobile OWA for IPhone was available for few weeks, but for Android it’s quite fresh.
After installation of Mobile OWA you can easily get access to your mailbox like using OWA on desktop computer.
With Mobile OWA you can access to all mailboxes where you have full access rights.
If you are using few mailboxes it’s better than Active Sync where you can use only one default mailbox