COM Add-ins Not Working in New Outlook: Why and What to Do

Why are COM add-ins not working in new Outlook?#

If your add-ins disappeared the day you switched, nothing is broken and nothing is misconfigured. COM add-ins are not working in new Outlook because the new client cannot load them at all. New Outlook for Windows is built on web technology, and it supports exactly one extension model: web add-ins.

COM and VSTO add-ins are Windows desktop code. They load into the classic Outlook process, talk to its object model directly, and draw their own ribbon buttons and panes. New Outlook has no desktop process for them to load into, so there is no toggle, repair or registry key that brings them back.

This is not a "not yet" item either. Microsoft's own feature comparison lists COM and VSTO add-ins as unsupported in new Outlook, alongside VBA macros, custom forms, voting buttons, importing and exporting rules, and attaching files straight from a network share.

The losses people notice within the first hour are the add-ins wired into another system: Salesforce and other CRM sidebars, DocuSign and e-signature panes, dictation and transcription tools, document management, time tracking. Those are precisely the tools most likely to have been built as COM add-ins in the first place.

What actually caused your add-in to disappear?#

Not every missing add-in is a COM add-in, and several of the causes below take two minutes to fix. Only the first has no fix at all. Confirm which one you have before doing anything drastic.

The distinction that matters is not which vendor built the add-in, but which extension model it uses. One is desktop code; the other is a sandboxed web app described by a manifest. They are not versions of the same thing.

How to audit your add-ins before you switch#

This is the part almost no guide gives you, and it is the only work that actually answers the question you care about: can I switch without breaking my day? Do it in classic Outlook, before you flip the toggle. It takes about twenty minutes.

1. 1

   List every add-in you actually have

   In classic Outlook, go to File, Options, Add-ins. The list shows active, inactive and disabled items with a type against each one. Screenshot it — this is your master list, and it is easier to capture now than after you switch.

2. 2

   Split the list into COM and web

   Set the Manage dropdown at the bottom to COM Add-ins and click Go for the desktop ones. Anything already listed as a web add-in will work in new Outlook unchanged. The COM list is where all of your risk sits.

3. 3

   Rank them by how often you use them

   Mark each one daily, weekly or rarely. A CRM sidebar you use forty times a day decides your switch. A reporting add-in you open each quarter does not, and should not be allowed to hold up the decision.

4. 4

   Check whether the vendor ships a web add-in

   Search the vendor name in Microsoft AppSource, then read the vendor's own support page for the words new Outlook or Outlook on the web. Vendor documentation is far more current than forum answers, which age badly in this area.

5. 5

   Test it in Outlook on the web first

   Outlook on the web uses the same web add-in model as new Outlook. Install the web add-in there and run one real task with it. That is a free preview of switch day, and you can do it without changing your desktop client at all.

6. 6

   Compare capability, not existence

   A web version frequently does less than the COM one it replaces. Run the specific job — log this email to an opportunity, send this for signature, dictate this reply — rather than checking that a pane opens.

7. 7

   Write a verdict against each add-in

   Four buckets: works, works with less, no equivalent, replaceable another way. Most lists resolve quickly. Only the no-equivalent bucket can block you, and it is usually shorter than people fear.

8. 8

   Decide from the blockers, not the count

   One unreplaceable daily add-in outweighs ten you never open. No blockers means switch. One blocker means work through the options in the next section before you force the move.

What to do when a vendor has no web add-in#

Some vendors have shipped nothing, and some never will. That is a real dead end for the add-in, but rarely for the workflow. These are the options in the order most people should try them.

It is worth understanding why the web version often does less, because it tells you which gaps will close and which will not. A web add-in runs sandboxed, talks to the mailbox through a defined API, and cannot reach into the rest of your PC. That is also what makes it safer and what lets it work on the web and on a phone.

Which Outlook clients support which add-ins?#

Add-in advice goes wrong when it forgets to say which client it applies to. Here is the whole picture, as of July 2026. Only one column of one row supports COM add-ins at all.

Should you switch, or stay on classic Outlook?#

Plenty of the advice circulating says you have to move now because classic Outlook is about to be switched off. As of July 2026 that is not accurate, and deciding under a deadline that does not exist is how people end up breaking a working setup.

Microsoft's published migration model has three stages — opt-in, then opt-out, then a final cutover — with at least twelve months' notice before each stage reaches production. New Outlook became the default for small and medium business in January 2025 with the ability to switch back; enterprise opt-out is scheduled for 1 March 2027. Existing classic installs are supported through perpetual and subscription licensing until at least 2029, and no firm cutover date has been announced.

One date is firmer, and it only affects Mac users: legacy Outlook for Mac retires for Exchange Online accounts in October 2026. Verify both of these on Microsoft's own pages before you plan around them, since this is the part of the story that changes.

So the honest answer for a lot of readers is: stay on classic while it is supported, and re-check your blocked add-ins every quarter. That is a legitimate decision, not procrastination.

• Switch now if every add-in you use daily already has a web version, or the COM ones are things you open twice a year.
• Switch now if you mostly live in mail, calendar and search, and want the client that gets new features first.
• Stay on classic if a COM add-in sits in your daily path — CRM logging, e-signature, dictation, document management.
• Stay on classic if you depend on VBA macros, custom forms, voting buttons, rules import and export, or attaching from a network share.
• Either way, keep classic installed while you can, and set a quarterly reminder to re-check the vendors that blocked you.

Where AI Emaily fits, and where it does not#

To be direct: AI Emaily does not run COM add-ins either, and it is not a replacement for a Salesforce or DocuSign add-in. That code only runs inside classic Outlook, and nothing outside classic Outlook can change that. If CRM logging is your blocker, keep classic for it.

What AI Emaily is, is an AI email assistant built into a client that connects your Outlook or Microsoft 365 account alongside Gmail and IMAP accounts — the setup walkthrough lives at /docs/connect-outlook. It triages, summarises long threads, and drafts replies from a Personal Context you set yourself, with client profiles you control, rather than by reading through your past mail. In Copilot mode nothing sends without your approval, and every action has undo and an audit trail.

That solves a different problem from the one this article is about. If your add-in question is really a question about the hours the inbox takes, it is worth a look. If it is about logging deals to Salesforce, the answer is still classic Outlook or the vendor's web app.

The short version#

COM and VSTO add-ins do not work in new Outlook because it is a web-based client with a single, sandboxed extension model. That is permanent, not a gap waiting to be filled, and it takes VBA macros, custom forms and voting buttons with it.

Audit before you switch: list the add-ins, separate COM from web, check each vendor for a web version, and test it in Outlook on the web. Then decide from your blockers. If one of them matters every day and has no equivalent, stay on classic Outlook — you have time, whatever the headlines say.