The billing add-in button is missing. The macro that filed invoices does nothing. Nothing is broken - the new Outlook simply has no COM and no VBA, and that one fact ends a generation of office automation.
Classic Outlook grew an ecosystem: COM add-ins written in .NET, accounting integrations, CRM panels, label printers, SMS senders, and personal VBA macros recorded over years. All of it plugs into the desktop application through Windows technology. The new Outlook is a web app in a window, and web apps cannot load COM components or run VBA. This is not a setting you can enable. This page explains what replaces them - web add-ins - what to audit, and who must stay on classic because their tools have no web version.
Example panel - check each tool you use against its type, not its brand name.
COM is a Windows desktop technology: an add-in is a DLL loaded into the Outlook process, talking to the full object model. VBA lives inside that same desktop process. The new Outlook renders a web interface and runs web code in a sandbox; there is no desktop process to load a DLL into and no VBA host at all. Microsoft is not withholding a switch - the architecture cannot host them. Any guide promising to enable macros in the new Outlook is selling fiction. The migration question is therefore not how to move your add-ins, but whether web versions exist.
Web add-ins are built on web technology and run in both the new Outlook and modern classic builds. Microsoft and large vendors ship them through AppSource, and they cover popular services well - meeting tools, major CRMs, signature platforms. Their limits are real: they work per user and per message context, they cannot roam your whole mailbox like a desktop tool, they need the internet, and deep local integrations - talking to a local Tally database, a local label printer service, a file on disk - are exactly what the sandbox prevents. Small local tools from small vendors are the least likely to have web versions.
Beyond vendor add-ins, offices run invisible automation: a macro that saves attachments to a folder, a rule paired with a script, a custom form, a Quick Step tied to a COM action. These die silently in the new app - no error, just absence. Power Automate can replace some of it for Microsoft 365 mailboxes, because flows act on the server mailbox: save attachments to SharePoint or OneDrive, post alerts, file copies. That covers cloud-shaped jobs. Jobs that touch local files, local printers or local software have no cloud substitute and remain classic-only work.
You have three honest options. Stay on classic while the vendor develops one - ask for their roadmap in writing. Replace the tool with a competitor that ships a web add-in, after a real trial on your mail. Or split desks: the desks that need the tool stay classic, everyone else moves. What does not work is switching first and discovering the gap during billing week. Vendors serving Indian accounting and local hardware integrations have been slower to ship web add-ins, so for those desks classic Outlook is not legacy stubbornness - it is the only platform their tools run on.
Every switching disaster story in this area starts with skipping the audit. One hour in classic Outlook - list add-ins, list macros, list script tied rules, ask the team - produces the true blocker list. If it is empty, the new app's cleaner world is open to you. If it has even one daily-use item with no web version, your answer is classic for that desk, with a review date. That is the entire method, and the video's comparison helps you see which popular features exist on which side before you run it.
See both Outlook apps side by side in the full video - every difference shown on a real PC, step by step.
Watch Full VideoNo. The new Outlook has no VBA host and does not load COM add-ins. Macros and COM tools run only in classic Outlook.
Yes, web add-ins from AppSource generally run in the new Outlook and in modern classic Outlook builds, which makes them the migration friendly option when a vendor offers one.
For Microsoft 365 mailboxes, a Power Automate flow can save attachments to OneDrive or SharePoint. Saving to a local PC folder is a desktop shaped job that stays with classic Outlook.