If you're unable to export the mailbox for your account from the Outlook.com web site, this article will help you export a backup to a .pst file using the desktop version of Outlook. When you complete the export, the .pst file will include a copy of your email, contacts, and calendar up to the date you created the file.
Step 1 - Get classic Outlook
To export your Outlook.com mailbox you'll need to use the desktop version of Outlook. If you don't already have the desktop version of Outlook installed on your device, or you don't have access a desktop version of Outlook, you can sign up for a free 30-day trial of Microsoft 365 or ask someone to sign up on your behalf. Go to Try Microsoft 365 for free.
Step 2 - Add your account to Outlook
After you set up the trial and download the Microsoft 365 apps to your device, open the Outlook app and add your Outlook.com email to the app. See, Add an email account to Outlook.
Step 3 - Export the mailbox
After your account is set up in classic Outlook you can begin exporting the mailbox. Follow the steps in Export emails, contacts, and calendar items to Outlook using a .pst file.
Step 4 - Optional: view the .pst file in Outlook
Optionally, after you successfully completed the export, you can add the .pst file to Outlook to see the items. Follow the steps in Open and close Outlook Data Files (.pst).
