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COM add-ins - The tip of the Iceberg

Updated: Sep 18, 2023

It's official: The current Outlook, as we have known it for over two decades, is entering its final years. In this announcement, Microsoft officially declared the end of Outlook in its current form, specifically Outlook for Windows. These details will be crucial for IT managers as they plan the transition. In summary, we have just over two years to make this change. The opt-in, opt-out, and final cutover path are clearly outlined in the announcement.

However, a less emphasised detail can be found in the FAQ slide later in the announcement:

COM add-ins will not work across platforms and will not be supported in the new Outlook.

Any middle-aged developer would have written anywhere from 2 to a dozen of these COM add-ins in their careers. Not only was it a brilliantly creative way to integrate custom-built applications into Outlook, but many third-party software vendors also depended on this feature to expand their applications into Outlook. It enabled us to perform actions on emails, attachments, or add functionality directly to the Outlook menu bar.

When the COM add-in template was first made available in Visual Studio (known as Visual Studio Tools for Office, or VSTO) back in the early 2000s, it was a game-changer for developers. Creating a COM add-in became an easy challenge for most .NET developers to master, and we enthusiastically embraced it. We could now run our own code from a right-click on an email or directly from the Outlook menu bar. It was the bridge that connected Outlook directly to your own solution.

Reading between the lines of the announcement, it would be a fair assumption to make that Outlook will become much more dependent on the cloud. In fact, this might be the underlying message behind discontinuing COM add-ins – migrate to Exchange Online or risk operating without it in your business.

However, the true iceberg lurking beneath the surface of this issue is the multitude of third-party products that rely on that clever little Outlook menu item. While the replacement for COM add-ins is web add-ins, they are not yet as feature rich as COM. Microsoft does have two years to bring them up to par. But even more concerning is the prospect that, if your third-party product provider does not plan a migration from COM to web add-ins, your users will lose that functionality in two years' time. Equally worrisome is the source code for some COM add-ins, which may have been created by a lone developer who has long since departed from the business.

As an IT manager, you need to assess that risk. While migrating to the new Outlook within two years might be feasible, is the migration from a legacy document management platform or your legal case management platform equally attainable?

In the worst-case scenario, this small deprecated link between Outlook and a critical line-of-business system could have a significant impact on your business.

Gabriel Malherbe

Gabriel Malherbe is a management executive at First Technology Digital. First Technology and First Technology Digital provide advisory services to clients on strategic IT roadmaps. We specialise in planning, implementing, and supporting strategic and customized software solutions for our clients.

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