Outlook Problems · New Outlook
New Outlook missing features from classic? Here's how to get them back
If the new Outlook has dropped something you relied on - a COM add-in, advanced or client-only rules, or certain shared-mailbox behaviours - you're not imagining it. Those features aren't all in the new Outlook yet. The quick answer: toggle "New Outlook" off to return to classic, which is supported until at least 2029. Here's exactly what's missing and how to switch back.
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What the new Outlook is still missing from classic
Microsoft is rebuilding Outlook, and the new version is faster and cleaner - but as of 2026 it hasn't caught up with everything classic Outlook does. If your workflow leans on any of these, that's why it feels broken:
- COM add-ins. The old-style add-ins that hook into CRM, accounting, dictation and line-of-business tools don't run in the new Outlook - it only supports newer web add-ins. If your practice-management or billing plug-in has vanished, this is why. There's no converting them on your end; the vendor has to ship a web add-in version.
- Advanced rules. The simplified rules engine drops some complex, multi-condition and "client-only" rules that run on your PC rather than the server. Quick Steps - those one-click move/flag/forward automations - are now in the new Outlook, under Quick steps on the Home tab.
- Local PST files (improving). The new Outlook can now open a PST so you can read old mail, but only with classic Outlook installed alongside (same 32-bit/64-bit architecture) and a Microsoft 365 subscription on the account. Microsoft's feature list (last updated September 2026) now says mail, calendar, contacts and tasks can be imported from a PST, though some classic PST features are still missing. If you archive to, or rely heavily on, local PSTs day to day, classic is still the safer home for now.
- Certain shared-mailbox behaviours. Some shared and delegated mailbox features don't behave the same yet - a known one is categories not showing on messages in a shared mailbox, plus assorted permission and new-mail-count quirks.
None of this means the new Outlook is bad - it means it isn't finished. If you don't touch any of the above, staying on new Outlook is perfectly fine.
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01Check what's missing
Confirm the feature you need - COM add-ins, advanced or client-only rules, or shared-mailbox behaviours - isn't yet in the new Outlook.
Is it working now? -
02Find the New Outlook toggle
Open the new Outlook and locate the New Outlook switch in the very top-right corner of the window.
Is it working now? -
03Turn the toggle off
Click the toggle to off, choose "Switch back to classic Outlook" at the prompt, then Outlook closes and reopens as classic.
Is it working now? -
04Let classic Outlook load
Classic reopens with your accounts, add-ins, rules and shared mailboxes intact and nothing lost, since mail lives on the server.
Is it working now? -
05Install classic if the toggle is missing
If the switch is greyed out or absent, install classic Outlook from your Microsoft 365 apps or ask us to set it up.
Is it working now? -
06Re-check the new Outlook periodically
Because Microsoft adds features over time, toggle back to new Outlook every few months to see if your feature has arrived.
Is it working now?
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New Outlook missing features from classic? Here's how to get them back - the fix order (365techies.co.uk/new-outlook-missing-features/) 1. Check what's missing: Confirm the feature you need - COM add-ins, advanced or client-only rules, or shared-mailbox behaviours - isn't yet in the new Outlook. 2. Find the New Outlook toggle: Open the new Outlook and locate the New Outlook switch in the very top-right corner of the window. 3. Turn the toggle off: Click the toggle to off, choose "Switch back to classic Outlook" at the prompt, then Outlook closes and reopens as classic. 4. Let classic Outlook load: Classic reopens with your accounts, add-ins, rules and shared mailboxes intact and nothing lost, since mail lives on the server. 5. Install classic if the toggle is missing: If the switch is greyed out or absent, install classic Outlook from your Microsoft 365 apps or ask us to set it up. 6. Re-check the new Outlook periodically: Because Microsoft adds features over time, toggle back to new Outlook every few months to see if your feature has arrived. Still stuck? 365 Techies fix it remotely: 01202 775566 - https://365techies.co.uk/remote-support/// NEED THIS FIXED RIGHT NOW?
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The fix
How to switch back to classic Outlook
The good news: getting your features back takes seconds, and you don't lose anything - your mail is on the server.
- Find the toggle. Open the new Outlook and look at the very top-right corner for the New Outlook switch.
- Turn it off. Click the toggle so it reads off. Outlook shows a short prompt - choose "Switch back to classic Outlook" and give a quick reason if asked - then it closes and reopens as classic Outlook.
- Let classic load. Classic reopens with your accounts intact. Your COM add-ins, local PSTs, advanced rules, Quick Steps and shared-mailbox setup come back with it.
- Can't see the toggle? If the switch is missing or greyed out, your organisation may control it - or classic may not be installed. You can install classic from the Microsoft 365 apps, or we can set it up for you.
How long is classic supported? Classic Outlook in Microsoft 365 or Office 2024 is supported until at least 2029, so for those versions switching back is a stable choice, not a stopgap; Outlook 2016 and 2019 support ended in October 2025, and Outlook 2021's support end date is 13 October 2026. And because the new Outlook gains features over time, it's worth toggling back to new every few months to see whether the thing you need has landed.
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// GOOD QUESTIONS
Frequently asked
Why is my Outlook add-in missing in the new Outlook?
The new Outlook doesn't run classic COM add-ins - the old-style plug-ins that hook into CRM, accounting or dictation tools. It only supports newer web add-ins, and existing COM add-ins can't be converted by you - the vendor has to release a web version. If your business plug-in has disappeared, switch back to classic Outlook using the toggle in the top-right corner and it'll return.
Can I open a PST file in the new Outlook?
Increasingly, yes. The new Outlook can open a PST so you can browse old mail, but only with classic Outlook installed alongside (same 32-bit or 64-bit build) and a Microsoft 365 subscription on the account. Microsoft's feature list (September 2026) now says mail, calendar, contacts and tasks can be imported from a PST, though some classic PST features are still missing. If you depend on local PSTs day to day, classic remains the more reliable choice today.
How do I switch back to classic Outlook?
Open the new Outlook and click the New Outlook toggle in the very top-right corner so it turns off. Outlook shows a brief prompt - pick "Switch back to classic Outlook" - then closes and reopens as classic, with all your accounts, add-ins and rules intact. Nothing is lost because your mail lives on the server.
Is classic Outlook going away?
Not for most people yet. Classic Outlook in Microsoft 365 or Office 2024 is supported until at least 2029, so for those versions switching back is a stable, long-term choice; Outlook 2016 and 2019 support ended in October 2025, and Outlook 2021's support end date is 13 October 2026. On those versions there is plenty of time to move across as the new Outlook matures.
Are advanced rules and shared mailboxes really different in new Outlook?
Yes. The new Outlook uses a simplified rules engine that drops some complex, multi-condition and client-only rules, though Quick Steps are now available. A few shared-mailbox behaviours - like categories showing correctly on messages - aren't fully in either. If you depend on these, classic Outlook is the right home for now.
Which Outlook should I be using?
It depends on what you rely on. If you use COM add-ins, advanced rules, local PST files or heavy shared-mailbox work, stay on classic. If you don't, the new Outlook is fine and only getting better. Not sure? Call 01202 775566 and we'll get you on the right version, usually the same day.
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