Change is afoot for the app everyone in your organization uses all the time as the long-awaited new version of Outlook is almost here and it’s time to get serious about preparing for its impact. The new Outlook represents a significant shift for end users across all platforms, as the email and calendaring app used by hundreds of millions of people modernizes on a web-based architecture. Now, regardless of device or platform, all Outlook users will have the same fundamental user experience and capabilities.

This platform consolidation has plenty of positives for end users from faster security updates to universal offline functionality. One of the biggest changes impacts add-ins, which allow third-party and in-house developers to build extensions for Outlook that add new capabilities and clever integrations with other apps. The new model makes it faster and easier to build add-ins, which will now work across all supported platforms rather than just Windows. But when organizations eventually cut over to the new Outlook, legacy add-ins won’t work without a major overhaul.

Many of these add-ins are used heavily, delivering must-have functionality for end users, so IT leaders looking to avoid disruptions must get proactive about ensuring business continuity. That means taking a long, strategic look at their add-in ecosystem and planning ahead to ensure minimal impact on business performance.

What’s changing in the new Outlook?

The new Outlook relies on a web client at its core, with platform-specific apps providing the local “frame” for that experience. In short, it means the browser-style version of Outlook will be replicated across platforms for a unified user experience. But for this discussion, the big change is discontinuing the COM/VSTO extensibility model for add-ins.

What’s the difference between web add-ins and legacy add-ins?

The old guard, COM/VSTO add-ins are specific to Outlook for Windows and install code locally. Web add-ins run in the context of the browser or webview of the new Outlook, exclusively, which means they work when accessing Outlook via a browser, on a Mac, or on any other platform running Outlook.

With web add-ins, Outlook checks the manifest and enables any UI elements or controls the add-in requires. The web add-in itself only loads JavaScript and HTML to deliver the user experience.

Will existing Outlook add-ins work on the new Outlook?

Well, it depends. Microsoft has provided both the web add-in model for a while, so some companies have already migrated or have built new web add-in versions of existing COM/VSTO add-ins. However, legacy COM/VSTO add-ins are useless for new Outlook users.

However, it’s important to keep in mind that COM/VSTO add-ins will keep working on the older, Windows-only version of Outlook. This can be a stop-gap measure, but eventually, your organization must migrate to the new Outlook to take advantage of functionality, security enhancements, and web-only add-ins with the features and capabilities your business demands.

What must change for existing Outlook plug-ins to work with the new Outlook?

Web add-ins don’t need to do anything, they’ll automatically work with the new Outlook. COM/VSTO add-ins, however, require some pretty significant changes to function with the new Outlook and must essentially be rewritten for the web add-in model.

What does this mean for you?

As an IT leader, it’s time to get proactive about your add-in transition strategy. Here’s a playbook for ensuring minimal disruption when the inevitable transition to the new Outlook occurs.

• Perform an audit of all add-ins currently in use, determining whether they’re web or COM/VSTO add-ins.
• Identify any mission-critical or heavily used COM/VSTO add-ins.
• Check to see whether the vendors of any third-party add-ins in use already provide a web version of their add-ins (many already offer these, such as Salesforce, Jira, and Zoom).
• For those vendors not currently offering web add-ins, check to see if it’s already on their public product roadmap, or contact your account manager to see if and when they’ll offer web add-in support.
• If they’re not planning a web add-in version, begin shopping around for alternatives.
• For any actively used add-ins developed internally, communicate this new requirement and work backward from your intended cut-over date to ensure those updates will be available beforehand to minimize disruption.
• Going forward, only approve and/or purchase web add-ins.

What does this mean for harmon.ie customers?

The future is bright for harmon.ie users because we’ve been working with Microsoft for years in anticipation of this transition. A preview of harmon.ie’s web add-in is already available for download, giving early adopters of the new Outlook a chance to see what’s coming down the line. As the harmon.ie web add-in matures, we’ll not only match current functionality but add even more capabilities.

Don’t let the downstream ramifications of the new Outlook take your organization by surprise. Begin planning now to make sure your business productivity isn’t negatively impacted by lining up web add-in replacements for the legacy add-ins your end users rely upon and start getting everyone excited about the new unified experience.