Two versions, one mailbox. Your email, calendar and contacts are exactly the same in both. What changes is mostly the look, where a few things live, and a small number of features that are still on their way. Here is the picture at a glance.
KeyOutlook ClassicNew OutlookStays the sameWorks differentlyNot yet in New
01
How each one works
This is the difference underneath the surface, and it explains why offline working behaves differently between the two.
Outlook Classic
A program on your PC
Keeps a full copy on your machine, so it works well offline and syncs up when you reconnect.
New Outlook
One experience, everywhere
Built like a website, so it looks the same across devices but needs an internet connection to work fully.
02
What changes, what stays
Most of what you do every day carries straight over. A few things have moved or behave differently, and a short list is still being added to the New Outlook.
Stays the same
Your emails, calendar and contacts Same mailbox, nothing is moved or lost
Your folders
Search, flags and categories
Reporting junk and phishing Now works in shared inboxes too
Rules Most carry over, a few may need redoing
Works differently
The look and feel Cleaner, more modern layout
Settings have moved Now behind the gear icon, not File then Options
Some buttons renamed or relocated
Search wording A few advanced search terms differ
Not yet in New
Full offline working Limited compared with Classic
Quick Steps One-click automations
Older add-ins Some third-party plug-ins are not supported
PST archive files Handling is more limited for now
03
Where things moved
If you switch over, here is where to find the handful of things that have changed places.
1
Report buttonsits top left, for flagging junk or phishing in one click.
2
Settings (gear icon)top right, this replaces File then Options.
3
New Outlook toggletop right, flick it to switch back to Classic any time.
4
Folders and messagesstay where you expect, on the left and centre.
04
Which should I use?
You are not locked in either way. Use the toggle to move between them while you decide.
Best for most people
Go with New Outlook
You mainly do everyday email, calendar and contacts
You like a cleaner, simpler layout
You want the newest features as they arrive
You report from a shared inbox
Stay here for now if
Keep Outlook Classic
You often work offline with no connection
You rely on a specific older add-in or plug-in
You use Quick Steps or heavy automation
You work with PST archive files day to day
Do I need to switch right now?
No rush. You have plenty of time.
New Outlook is where Microsoft is adding all the new features, but Classic is not going anywhere soon. Move when you are ready.
NOW
Both available. Switch freely using the toggle in the top right corner.
THROUGH 2026
New keeps improving. Missing features and shared mailbox controls continue to arrive.
2028 ONWARDS
Classic stays supported well beyond this, so there is no cliff edge.