How to Switch Back to Classic Outlook (and Keep It There)

How do you switch back to classic Outlook?#

In new Outlook for Windows, the New Outlook toggle sits at the top right of the window. Turn it off, choose Switch back to classic Outlook in the dialog that appears, and classic opens. That is the whole procedure.

It is also a supported one. Microsoft's migration guidance says users can revert during the current stages, and that both clients can run side by side. Going back is a normal choice, not a hack you are getting away with.

Two things stop it working: classic Outlook has to be installed, and your organisation has to have left the toggle in place. Everything below is labelled by client, because this toggle exists only in new Outlook for Windows — Mac, web and mobile work differently.

What carries over, and what doesn't#

Almost everything people fear losing is stored in the mailbox rather than the app. On a Microsoft 365, Exchange Online or Outlook.com account, mail, calendar, contacts, folders and server-side rules live on the server, and both clients are windows onto the same data.

What does not survive is what you created inside new Outlook. Microsoft documents the move into new Outlook as migrating your classic accounts and settings across. It documents no migration in the other direction.

Steps: switching back in new Outlook for Windows#

New Outlook for Windows only. Under a minute of clicking, plus however long your classic profile needs to catch up.

1. 1

   Confirm classic is installed, then prepare

   Look for Outlook (classic) in the Start menu — no install, no toggle. Then let new Outlook finish syncing, copy out any signature you built on a non-Microsoft account, and list every account you added while you were here.

2. 2

   Turn the New Outlook toggle off

   It is at the top right. Microsoft shows a dialog rather than switching immediately, and the two options it offers do genuinely different things.

3. 3

   Choose Switch back to classic Outlook, not Use classic Outlook this time

   The first makes classic the version that opens from now on. The second opens classic once and leaves new Outlook as your default — which is the most common reason a switch appears not to stick.

4. 4

   Answer or skip the feedback prompt

   Microsoft asks why you are leaving every time you toggle back. It is optional, and it feeds the gap list your admin can see in the Microsoft 365 admin center, so a named add-in beats an empty box.

5. 5

   Let classic finish its first sync

   A profile idle for weeks needs a few minutes to catch up. Do not start cataloguing what is missing until send and receive has completed.

6. 6

   Re-add your accounts and restore signatures

   Classic connects IMAP and Gmail accounts directly to the provider, while new Outlook syncs them through the Microsoft Cloud — different connections, not two views of one setup. Microsoft 365 signatures normally roam back; IMAP and on-premises ones do not.

7. 7

   Pin classic and check your default mail app

   Pin Outlook (classic) to the taskbar, then check the Windows default apps setting for mail. Otherwise the next mailto link opens new Outlook and makes the switch look like it failed.

Why the switch to classic Outlook toggle is missing or greyed out#

This is the case consumer guides skip, and it is not something you can click your way out of. Microsoft gives administrators explicit control over both directions of the toggle. When a policy is set against your account, the option is genuinely absent rather than hidden somewhere clever.

What decides your afternoon is not which version you prefer. It is which of three routes out of new Outlook you are on: the toggle works, the toggle works but a policy keeps reversing you, or the toggle has been removed from your account.

What to ask IT for when the toggle has been removed#

The outcome depends almost entirely on how you ask. A preference for the old interface loses. A named business workflow that has stopped working usually wins an exception, because that is the language the migration project already uses. Naming the policy saves your admin a lookup, too.

What you get back, and what stops working#

Switching back restores every classic-only capability, because none of them were removed from classic in the first place. Accurate as of July 2026 — check Microsoft's feature comparison before you plan around a row.

The add-in row sends most people back, and it deserves a real audit rather than a table cell — we cover that in a separate post on COM add-ins not working in new Outlook. Check whether your vendor already ships a web add-in before deciding classic is permanent.

Read the last row honestly too. New Outlook gets new capability first, and some of it will not be back-ported. Going back is a trade you are making on purpose.

Switching back on Mac, the web and mobile#

Everything above is Windows-specific. The other clients answer differently, and one carries a date that is firmer than anything in the Windows story.

How long can you stay on classic Outlook?#

Longer than the headlines suggest. Microsoft's model has three stages — opt-in, then opt-out, then cutover — with at least twelve months of notice, through existing admin channels, before each reaches production rings.

New Outlook became the default for small and medium business in January 2025, with reverting still possible. Enterprise opt-out is scheduled for 1 March 2027. Both are the opt-out stage, where switching back is part of the design rather than an oversight.

Cutover is the stage where the toggle goes for good. No date for it has been announced, and Microsoft's guidance states that existing classic installs through perpetual and subscription licensing are supported until at least 2029. Verify on Microsoft's own page before planning around any date, including the ones here.

Using the time well#

• Re-check your blocked vendors quarterly. Web add-ins ship on the vendor's schedule, not Microsoft's.
• Test in Outlook on the web. It uses the same web add-in model as new Outlook, so it previews switch day without touching your desktop.
• Move repeatable macros to Power Automate or a Microsoft Graph script now, while a working classic install is still there to compare against.
• Keep classic pinned and keep using it. Staying breaks no rule unless your own organisation says so.
• Watch for the notice of disruptive change. That is the twelve-month signal, and it reaches IT before it reaches you.

One note about what this page is not#

This is aiemaily.com, so plainly: AI Emaily is a separate email client, it does not run COM add-ins or VBA macros either, and it is not a route back to classic behaviour. If an add-in or a macro sent you here, classic Outlook is the answer.

For completeness, we build an AI assistant inside a client that connects Outlook, Gmail and IMAP accounts side by side, drafting from a Personal Context you set rather than from your old mail, with approval before send, undo and an audit trail. Different problem from this one.

The short version#

Use the toggle at the top right of new Outlook for Windows and choose Switch back to classic Outlook, not Use classic Outlook this time. Classic has to be installed for the toggle to exist.

Your mailbox comes with you; anything configured inside new Outlook does not, so copy out signatures and list added accounts first. A missing toggle is a policy on your account, and the fix is a specific request to IT rather than a registry edit — and you have until at least 2029, with twelve months of notice before the stage that removes the choice.