Summary

Microsoft currently offers three versions of Outlook for Windows: Classic Outlook (the traditional desktop app), New Outlook (the modern redesigned app), and Outlook on the Web (browser-based). Each version has different features, capabilities, and limitations. This article explains what each version is, how to tell which one you are using, and when to use which.

In this guide

• 1. The Three Versions at a Glance
• 2. Feature Comparison — What Works Where
• 3. How to Tell Which Version You Are Using
• 4. How to Switch Between Classic and New Outlook
• 5. Decision Guide — "Which Outlook Should I Use?"
• 6. Common Confusion Points

Before You Start

• A Microsoft 365 work or school account.
• Windows 10 or Windows 11.

Instructions

1. The Three Versions at a Glance

	Classic Outlook	New Outlook	Outlook on the Web
What it is	The traditional Win32 desktop application that has been the standard for 20+ years	A modern, lighter desktop app built on web technology (same engine as Outlook on the Web)	The browser-based version at outlook.office.com
How to open it	Start menu → "Outlook" (shows the classic blue Outlook icon)	Start menu → "Outlook (new)" or toggle the "Try the new Outlook" switch in Classic Outlook	Open a browser → go to outlook.office.com
Install required?	Yes — included with Microsoft 365 Apps for Enterprise	Yes — bundled with Windows 11 or installed from the Microsoft Store	No — runs in any modern browser
Offline access	✅ Full offline support — cached email, calendar, contacts	✅ Limited offline support (recent emails and calendar)	❌ Requires internet connection
Data storage	OST file stored locally on your hard drive	Cloud-based (minimal local cache)	Cloud-based (nothing stored locally)
Update cadence	Monthly Channel (organizations control the update schedule)	Updated automatically and frequently by Microsoft	Updated continuously by Microsoft

2. Feature Comparison — What Works Where

This table covers the features users ask about most. A ✅ means the feature is fully supported, 🔶 means partial or limited support, and ❌ means not available.

Feature	Classic Outlook	New Outlook	Outlook on the Web
Email rules	✅ Full rules engine (client-side + server-side)	✅ Server-side rules only	✅ Server-side rules only
Quick Steps	✅ Full support	🔶 Partial — work/school accounts only, no shared mailboxes	❌ Not available
Focused Inbox	✅	✅	✅
Email signatures	✅ HTML signatures with images	✅ Signatures (may have limited formatting compared to Classic)	✅ Signatures (web editor)
Shared mailboxes	✅ Full support (auto-mapped or manual)	✅ Supported	✅ Supported
Delegate access	✅ Full delegate management	🔶 Limited — delegate features are still rolling out	✅ Supported
Calendar	✅ Full calendar with room finder, scheduling assistant	✅ Full calendar	✅ Full calendar
Room Finder	✅	✅	✅
Out-of-office replies	✅	✅	✅
Mail merge	✅ (via Word integration)	❌ Not available	❌ Not available
COM Add-ins	✅ Full COM add-in support	❌ Not supported — uses web add-ins only	❌ Not supported — uses web add-ins only
Web add-ins	✅	✅	✅
PST file import/export	✅ Full PST support	✅ Import and export supported (opening a PST needs Classic installed)	❌ Not available
Advanced search	✅ (AQS search syntax)	✅ (simplified)	✅ (simplified)
Multiple Exchange accounts	✅	🔶 Limited	❌ One account per browser session
POP/IMAP accounts	✅	🔶 IMAP supported, POP is limited	❌ Microsoft 365 and Outlook.com only
S/MIME encryption	✅	🔶 Rolling out	🔶 Requires S/MIME extension
Copilot integration	🔶 Available in supported plans	✅ Full integration	✅ Full integration

Note: New Outlook features are actively evolving. Microsoft is progressively adding Classic Outlook capabilities to New Outlook. Features marked as ❌ or 🔶 today may become ✅ in future updates. This table was last verified on 2026-08-03.

3. How to Tell Which Version You Are Using

Classic Outlook:

• The title bar says "Microsoft Outlook" or shows your mailbox name.
• The ribbon has the traditional multi-row toolbar with tabs (Home, Send/Receive, Folder, View).
• The File tab in the top-left opens a full backstage view with Account Settings, Options, and Office Account.
• You will see a toggle switch in the top-right corner labeled "Try the new Outlook" — if this toggle exists, you are in Classic.

New Outlook:

• The title bar says "Outlook (new)" or "Outlook" with a simplified, modern look.
• The ribbon is a single, simplified toolbar with fewer options.
• There is no File tab or backstage view. Settings open in a side panel.
• You may see a toggle to "Switch to Classic Outlook" in Settings.

Outlook on the Web:

• You are in a browser (Edge, Chrome, Firefox, etc.).
• The URL is outlook.office.com or outlook.office365.com.
• The interface looks very similar to New Outlook (they share the same design engine).

4. How to Switch Between Classic and New Outlook

From Classic → New Outlook:

1. In Classic Outlook, find the "Try the new Outlook" toggle in the top-right corner of the window.
2. Flip the toggle on.
3. Outlook will restart and open in New Outlook mode.

From New → Classic Outlook:

1. In New Outlook, click the gear icon (⚙️) to open Settings.
2. Scroll down and look for "Switch to Classic Outlook" or "Go back to Classic Outlook".
3. Click it. Outlook will restart in Classic mode.

Note: Your organization may control whether you can switch between versions. If the toggle is missing, your IT department may have locked your Outlook version via policy. Ask IT to unlock the version toggle for your account, and name the version you need and the feature driving it — for example, "I need Classic Outlook for the COM add-in my team uses."

5. Decision Guide — "Which Outlook Should I Use?"

Scenario	Recommended Version	Why
Standard email, calendar, and Teams user	New Outlook	Modern, fast, Copilot-ready, lighter on system resources
Heavy email user needing COM add-ins, mail merge, or full offline access	Classic Outlook	These remain Classic-only. Quick Steps and PST files now work in New Outlook, with limits — see the table above
Using a shared computer or someone else's device	Outlook on the Web	No install needed, nothing stored locally, sign out when done
Working from a personal device without Microsoft 365 installed	Outlook on the Web	Full functionality in any browser, no install required
Need full offline access for travel or unreliable internet	Classic Outlook	Best offline support with full local data cache
IT admin recommended Classic for compatibility	Classic Outlook	Follow your organization's guidance — some line-of-business add-ins require Classic
Want the latest features and Copilot integration	New Outlook	New features and AI capabilities ship to New Outlook and Web first
Managing multiple POP/IMAP personal accounts	Classic Outlook	Best support for non-Microsoft email protocols

6. Common Confusion Points

"Why do my Quick Steps not work anymore?" New Outlook has Quick Steps, but they do not carry over from Classic — you rebuild them under Settings > Mail > Quick Steps. For guidance, see How to Use Quick Steps in Outlook. They also work only on a work or school account, so a personal Outlook.com, Gmail, or Yahoo account in New Outlook has no Quick Steps at all, and they do not run on shared mailboxes. If any of those apply to you, recreate the workflow as an email rule or stay on Classic.

"Why does New Outlook look exactly like the web version?" Because New Outlook is built on the same codebase as Outlook on the Web. Microsoft is converging the two experiences. The main difference is that New Outlook is a standalone desktop app with offline support and system notifications, while the web version runs in a browser.

"Will Classic Outlook go away?" Microsoft has stated that New Outlook will eventually replace Classic Outlook, but there is no hard end-of-life date for Classic yet. Organizations that rely on Classic-only features (COM add-ins, mail merge, full offline access) will have extended support. Check with your IT department for your organization's migration timeline.

"I lost my email rules when I switched to New Outlook" Client-side rules (rules that only run on your desktop, such as rules with "on this computer only" conditions) do not transfer to New Outlook because New Outlook only supports server-side rules. Recreate affected rules in New Outlook, or switch back to Classic to use them. For how the rules interface works in New Outlook, see How to Create Email Rules in Outlook.

"My add-in is missing in New Outlook" Classic Outlook uses COM add-ins (desktop-installed plugins). New Outlook only supports web add-ins (cloud-based plugins from the Microsoft Store). If your required add-in is COM-only, you need to use Classic Outlook until the add-in publisher releases a web version.

Troubleshooting

INFO

If you are unsure which version of Outlook your organization recommends, ask IT to confirm which version is standard for your role and whether you are allowed to switch. Some organizations standardize on Classic Outlook for compatibility, while others are migrating to New Outlook for Copilot and modern features.

Symptom / Error	Potential Cause	Solution
"Try the new Outlook" toggle is missing	Disabled by IT policy	Your organization has restricted access to New Outlook. Ask IT to enable the New Outlook toggle for your account, or to confirm the restriction is deliberate.
Quick Steps disappeared after switching to New Outlook	They do not transfer between versions	Rebuild them under Settings > Mail > Quick Steps. If that section is missing, you are signed in with a personal account — Quick Steps need a work or school account.
COM add-in not loading in New Outlook	Not supported	New Outlook does not support COM add-ins. Use Classic Outlook or check if the publisher offers a web add-in version.
Cannot open a PST in New Outlook	Classic Outlook is not installed, or is a different architecture	Opening a PST needs Classic Outlook on the same computer, both 32-bit or both 64-bit. Importing the PST instead brings the mail into your mailbox without that requirement. Outlook on the web cannot use PST files at all.
"Switch to Classic Outlook" option not available	Classic Outlook not installed	Install Microsoft 365 Apps for Enterprise via office.com/setup, or ask IT to install the Classic Outlook desktop app on your machine.
Signatures look different between versions	Different rendering engines	Each version has a slightly different HTML editor. Simplify your signature format (standard fonts, minimal images) for consistency.
Outlook feels slow or uses too much memory	Classic Outlook with a large OST file	Try New Outlook (lighter resource usage) or compact your OST file: File > Account Settings > Data Files > Compact.

Related Articles

• How to Use Email Basics in Outlook
• How to Create Email Rules in Outlook
• How to Use Focused Inbox in Outlook
• How to Use Quick Steps in Outlook
• How to Add a Shared Mailbox in Outlook
• How to Set Up an Out-of-Office Reply in Outlook
• How to Create an Email Signature in Outlook
• How to Fix Outlook Not Opening or Crashing

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