OWA or Mobile Outlook
I don’t know many Office 365 users who like accessing their email with OWA on a mobile device when Outlook mobile is available, but obviously some do. Perhaps they don’t like installing apps on their phone or use a non-standard mobile device that Outlook mobile doesn’t support, or they hark back to the days when OWA for Devices was the cornerstone of Microsoft’s mobile email strategy. In any case, folks in this category should note the news in Office 365 Notification MC202145 that the new OWA is becoming the only option for mobile browsers. This switchover happened for other browsers last July.
You can use the new OWA today with mobile browsers. What’s changing is that Microsoft is removing the toggle that allows users to switch between the new old and the older version (Figure 1). When this happens, users will only be able to access the new OWA. The changeover starts in February 2020 and should be complete by the beginning of March.
The change is a roadmap item (59334) and will relieve Microsoft from the need to maintain a separate code base for OWA for mobile browers.
Missing Features in New OWA
The list of not supported and won’t ever be supported features for the new OWA on mobile browsers is a lot more interesting than the loss of a toggle swatch. OWA is the fastest evolving of all the Exchange Online clients so there’s pressure to add new features and drop old features for the client in general. Mobile browsers introduce another decision point, which is the set of features available in the mainline versions of OWA to exclude because they are inappropriate in a mobile environment, won’t work, or can’t fit into the browser UI.
For example, in the list of unsupported features, there’s going to be no option to set message sensitivity and importance or assign retention policies. I assume that the way OWA handles sensitivity labels, especially when labels invoke encryption for messages, is one of the factors driving why sensitivity labels won’t be supported. Outlook mobile supports assigning sensitivity labels to new messages, but the processing is done on the server rather than in the client, which is what OWA does. Perhaps there’s no way to call the code to process encryption in a mobile browser context. Although I am surprised that OWA on mobile browsers won’t support retention labels, this is probably because most users don’t assign retention labels and leave it retention to organizational policies that execute in the background.
Other notable exclusions are that you can’t access Outlook add-ons in mobile browsers, or view shared folders or mailboxes, or shared calendars.
Use Outlook Mobile
The list of missing features underlines the argument to use Outlook Mobile (if possible). The iOS and Android variants both work well, are highly functional, and much faster than using OWA in a mobile browser. And with a 100+ million user base (as of May 2019), Outlook Mobile is the most popular choice for mobile email access for Office 365 users. Even if I can’t use some of Outlook Mobile’s party tricks (like Play My Emails), it’s still the best choice for most users.
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