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How to Switch from Microsoft 365 to Office 2021 Without Losing Outlook Data
Question details
The user wants to replace a Microsoft 365 subscription with a permanent Office Professional 2021 installation without losing Outlook profiles, OST files, emails, contacts, and calendar data.
- Product
- Microsoft 365 / Office Professional 2021
- Device & OS
- not provided
- Scenario
- Downgrading or switching from a subscription-based Microsoft Office plan to a one-time purchase version on the same computer.
- Observed behavior
- The user needs to ensure a seamless transition of email client settings and local data, preventing any data loss or profile corruption during the software replacement process.
Before uninstalling Microsoft 365, export any data stored in IMAP 'This Computer Only' folders to a PST file, as these are not synchronized with the server and will be lost if the OST cache file is reset.
Safely Replace Microsoft 365 with Office 2021
Follow these steps to remove your subscription version and install the perpetual license version while retaining your existing Outlook configurations.
Uninstalling Microsoft Office applications does not automatically remove Outlook profiles from your Windows system. Your existing profiles, along with Exchange-synchronized emails, calendars, and contacts, will remain intact and be automatically detected by Office 2021 once installed.
OST files act as server mirrors. If a new OST file ends up being required after the switch, Outlook will simply download your synchronized data again directly from the email server.
In your current Outlook, navigate to File > Open & Export > Import/Export. Choose 'Export to a file' and back up any folders marked as 'This Computer Only'.
Open Windows Settings > Apps > Installed apps. Scroll down to find Microsoft 365, click the three dots (or right-click), and select Uninstall.
Run the Office 2021 installer from your Microsoft account online dashboard or your physical installation media.
Open Outlook 2021. It will automatically load your existing profile and connect to the server to synchronize your emails, contacts, and calendar.
Log into your Microsoft account in a web browser, navigate to the Services & subscriptions page, and manually cancel your Microsoft 365 subscription to avoid recurring billing.
Try WPS Office: A Lightweight and Free Alternative to Microsoft Office
If you are reconsidering your Microsoft Office installation or subscription, WPS Office provides a powerful, free, and highly compatible alternative. It supports all major document formats and offers a familiar interface, making your transition seamless without the need for expensive licenses.
Frequently Asked Questions
Will I lose my emails if I uninstall Microsoft 365?
No. Uninstalling Microsoft 365 only removes the software applications. Your Outlook profiles, PST files, and server-synchronized Exchange or IMAP emails are preserved on your computer and the email server.
Do I need to recreate my OST files after installing Office 2021?
Normally, creating new OST files is unnecessary as Outlook 2021 will use the existing ones. If a new OST is created, Outlook will automatically re-download your data from the Exchange server, so you will not lose data.
How do I back up 'This Computer Only' folders in Outlook?
Go to File > Open & Export > Import/Export in Outlook. Choose 'Export to a file', select 'Outlook Data File (.pst)', and select the specific folders marked as 'This Computer Only' to back them up to a safe location before uninstalling.
Does installing Office 2021 automatically cancel my Microsoft 365 subscription?
No, installing a new perpetual version of Office does not affect your ongoing subscription. You must manually log into your Microsoft account online and cancel your Microsoft 365 subscription or disable recurring billing.
