New Outlook Vs Old Outlook: Everything You Need to Know
Published: June 19th, 2025 • 7 Min Read
Hello Folks, if you are reading this blog, then you might be interested in knowing the difference between new Outlook vs old Outlook. Microsoft has grabbed the attention of many of us by introducing new Outlook. This new version of Outlook aims to focus on an interactive and clean user interface with integration to cloud-first performance. Last year, in 2024, Microsoft replaced Windows Mail with the new Outlook. In continuation of this update, they are planning for Outlook Classic end of life.
This blog will guide you through the detailed side-by-side comparison of Classic Outlook vs New Outlook. In the detailed comparison, we will cover UI/UX, performance, compatibility with PST and COM add-ins, future updates, offline access, and much more. Therefore, it is suggested to read each section of this blog content to have an in-depth understanding of the topic.
New Outlook Vs Classic Outlook: Quick Comparison
| Features | New Outlook | Old Outlook |
| User Interface | Modern design that looks like you are working on the web or on your mobile phone | Old school ribbon-based design |
| Performance | Lightweight and fast | Heavier, slower with low-end systems |
| Platform Base | Cloud-based. Specifically based on WebView2 (Edge) | Build on Native Win32 architecture. |
| Add-ins Support | COM add-ins are not supported | COM add-ins supported |
| Rules and Automation | Basic Rule Setup | Advanced rules, macros, and quick steps are supported |
| Security & Compliance | Cloud-native encryption & policies, stricter email authentication requirements | Limited to legacy + modern security options. |
What is New Outlook? A Modern Cloud-Based Architecture
Based on Outlook on the Web (OWA): The new Outlook shares its look and feel with Outlook on the Web (formerly OWA). The motive behind the same UI/UX is to provide a feel to users across different platforms. Additionally, it is easier for users to learn new Outlook functionality who have already learned to use Outlook on the Web.
Work on WebView2: The new Outlook, as compared to the old Outlook, works on Microsoft Edge WebView2 as the rendering engine. It means the application behaves like a web-based application but runs on your desktop. This technique helps the new Outlook provide faster performance, lower memory usage, and advanced support for modern technology and security practices.
Cloud Native and Service Driven: Unlike the Old Outlook that heavily relies on OST/PST files for its functionality. Where users many times require OST to PST conversion. The New Outlook is a cloud native solution. Means the data is present on Microsoft’s Data Centres, not on the local device storage like Classic Outlook.
Unified Codebase (One Outlook Vision): This difference in new Outlook vs Classic Outlook is part of Microsoft’s one Outlook Vision. It aims to create a unified codebase for Outlook across different devices, including Windows, Mac, Web, and Mobile. This practice helps Microsoft to provide faster updates for the new Outlook across different devices.
Feature Difference Between New Outlook Vs Old Outlook
User Interface (UI/UX)
Outlook New: Developed with a modern, clean UI/UX based on Outlook on the web. Provide consistent UI across devices and platforms.
Outlook Classic: Built on a traditional ribbon-based interface, more feature-rich. But it is clutter for new users to understand the functioning.
PST File Support
Outlook New: Support to import PST files, but with limitations to view emails from the Outlook data files. The functionality to view other data, including contacts, calendars, and more still under development. However, there is no such export functionality till now.
Classic Outlook: Fully supports PST files for import/export. This feature helps users with easy backup and archiving.
Note: PST import functionality in New Outlook is only available if you have a subscription to Microsoft 365.
Offline Access Difference for New Outlook Vs Old Outlook
New Outlook: Limited offline support, the new version is more tilted towards a cloud-native solution approach.
Legacy Outlook: Full offline data access functionality. Once the data is synced properly, you can access it in offline mode.
Add-ins & Extensions
Outlook New: Modern web-based add-ins are supported. However, the old Outlook add-ins will not be going to work in the new Outlook. Developers are required to redevelop these plugins.
Old Outlook: Support all older COM/VSTO and modern web-based add-ins.
Rules, Automation & Macros
Outlook New: Limited support, advanced rules, and macros are not yet supported in the new Outlook.
Outlook Old: Full support for client-side rules, Outlook VBA macros, and complex automations.
Platform Architecture Difference for New Outlook Vs Classic Outlook
Outlook New: Developed on web-based architecture. It is mainly built on WebView 2 and React, which is used for its development.
Outlook Old: Completely desktop-based application built on traditional Windows architecture.
AI & Collaboration Tools
Modern Outlook: The new Outlook environment is deeply integrated with Microsoft 365 Copilot, Teams, Loop Component, etc.
Outlook Classic: Limited collaboration of AI tools unless you have a Microsoft 365 subscription.
Security & Compliance
Outlook New: Built with modern security, cloud-first compliance, and advanced phishing protection.
Old Outlook: Secure, but dependent on local configuration and less adaptive to real-time threats.
New Outlook Vs Old Outlook: Which is Better for You?
Based on the above discussion, we can conclude that you should choose New Outlook if you need to access your data on multiple devices and use Microsoft 365 for collaboration.
However, if you require rules, macros, and add-ins. Additionally, you need to work in offline mode with complete data access. You need to go with the old Outlook
Things to Remember When Switching from Outlook Classic to New Outlook
- Backup your PST files before switching via a reliable PST converter.
- Verify your add-ins’ compatibility in the new Outlook that you use regularly.
- Be habitual with the limitations of complete offline accessibility in the new Outlook.
- Familiarize yourself with the new modern UI/UX of the new Outlook.
Conclusion
In a detailed comparison of New Outlook Vs Old Outlook, we have clearly seen that Microsoft is clearly steering towards a unified cloud-first platform. The new Outlook simple, modern, and lightweight designs aim for high performance with collaboration to modern AI tools like Microsoft Copilot. In conclusion, you should stick to old Outlook for now if your workflow depends on offline accessibility and PST file control. If your aim is high performance with low dependence on offline accessibility, you should choose the New Outlook.
Frequently Asked Questions
Q1. Why is Microsoft pushing New Outlook vs Old Outlook?
Ans: Microsoft is promoting New Outlook vs Old Outlook as part of its broader “One Outlook” vision—a strategy to simplify, unify, and modernize the Outlook experience across all platforms (Windows, Mac, Web, and Mobile).
Q2. Which is more secure: New Outlook vs Old Outlook?
Ans: New Outlook is more secure as comparison to old Outlook since new Outlook works on a modern security model and cloud-first architecture. It offers features like:
- Real-time malware and phishing protection.
- Cloud-based email encryption.
- Direct support of Microsoft 365 compliance.
Q3. What is the future roadmap for New Outlook vs Old Outlook?
Ans: Microsoft is quickly rolling out the updates for the new Outlook. According to the Microsoft Roadmap, the major updates for New Outlook will be rolled out by the end of 2025. It also includes support to import/export PST files from the new Outlook.
Q4. Can I use the New Outlook and Old Outlook side by side?
Ans: Yes, you can use the New Outlook and Old (Classic) Outlook side by side, and Microsoft actively supports this during the transition period.