Microsoft has built native Outlook Web App clients for Apple's iPhone and iPad, both of which can be installed directly from the Apple App Store as of July 16.
The catch: Users need an Office 365 subscription that includes Exchange Online to make use of the new, free apps.
Outlook Web App (OWA) is a client with that provides email, calendar and contact functionality. It works the same way that Outlook Web App in the browser does. However, according to a new Office 365 Technology blog post from Microsoft, the native versions provide "additional capabilities that are only possible through native integration of the app with mobile devices."
From today's blog post:
"Windows Phone 8 comes with a top-notch native email client in Outlook Mobile, and we offer Exchange ActiveSync (EAS), which is the de-facto industry standard for accessing Exchange email on mobile devices. In order to better support many of our customers who use their iPhones and iPads for work, we are introducing OWA for iPhone and OWA for iPad, which bring a native Outlook Web App experience to iOS devices!"
The Office 365 plans which support Outlook Web App include: Office 365 Small Business; Office 365 Small Business Premium; Office 365 Midsize Business; Office 365 Enterprise E1, E3 and E4; Office 365 Kiosk K1 and K2; Office 365 Education A2, A3 and A4; and any Exchange Online plan. There are also Office 365 government plans that include OWA for iPhone and OWA for iPad. Users must be running iPhone 4S or higher or an iPad 2 or higher (both of which are running iOS 6 or higher) to use the new apps. The OWA apps are available in the same 60 languages supported by Exchange Online for Outlook Web App in the browser, according to Microsoft.
Microsoft introduced last month an Office Mobile for iPhone suite, which also requires an Office 365 subscription.
Update: A couple more related questions answered by a company spokesperson:
Q: When will on-premises be supported? Will there be an Outlook Web App that will run without the O365 requirement at some point?
A: Like Outlook Web App on the browser, OWA for iPhone and OWA for iPad have been developed for Exchange, and we’re leading with the cloud.
Q: So.... will there be support for Exchange on-premises coming?
A: Yes. See the information highlighted in yellow in this Exchange blog post, noting OWA for iPhone and iPad also will be available (but no date) for Exchange Server 2013.
Q: When will there be Android and Windows Store/modern version of OWA (for Windows RT and Windows 8)?
A: We have not announced plans to deliver OWA for Android or Windows. However, we already offer Exchange ActiveSync (EAS), which is the de-facto industry standard for accessing Exchange email on mobile devices and Windows Phone 8 comes with Outlook Mobile.
(Thanks to Windows SuperSite's Paul Thurrott for the tip-off about the OWA client availability.)