According to Microsoft, to add mobile support to your existing add-in, all you have to do is the following:
- Add-ins that support mobile must pass a strict set of validation criteria, so we encourage you to share your scenario ideas and mockups for pre-approval before you start implementation, using the form at https://aka.ms/outlookmobileaddin.
- Decide what scenarios to enable on mobile. Not every action makes sense on the small screen, so be sure you’re highlighting the most important functionality of your add-in for mobile. Keep in mind that only mail read scenarios are supported right now.
- Update your manifest to declare support for the Mobile Form Factor and define the actions you came up with in step 1.
- If applicable, make sure any backend calls to the mailbox are using our REST API. EWS requests are not supported on mobile.
- Build mobile-specific UI for the small screen using our design guidelines.
- Submit your add-in to the Office Store for validation. You can find instructions here.
Support for Android and Windows Mobile devices is coming soon too but Microsoft officials aren't announcing any exact dates for when the feature rollout on these platforms will start.
Microsoft also announced add-in support availability for the latest Office for Mac versions, including Word, Excel, PowerPoint and Outlook. You'll need to have Office for Mac build 170124 or newer installed. You can find new updates in the Office Store available from the Home tab.