Export to PST
At the top of your Outlook ribbon, choose File.
Choose Open & Export > Import/Export.
Choose Export to a file.
Click Outlook Data File (.pst)> Next.
Select the name of the email account to export, as shown in the picture below. Only information for one account can be exported at a time.
Make sure that the Include subfolders check box is selected. This ensures that everything in the account will be exported: Calendar, Contacts, and Inbox. Choose Next.
Click Browse to select where to save the Outlook Data File (.pst). Enter a file name, and choose OK to continue.
Note: If you’ve used export before, the previous folder location and file name appear. Type a different file name before choosing OK.
If you are exporting to an existing Outlook Data File (.pst), under Options, specify what to do when exporting items that already exist in the file.
Choose Finish.
Outlook begins the export immediately unless a new Outlook Data File (.pst) is created or a password-protected file is used.
Import PST
At the top of your Outlook ribbon, select File.
Select Open & Export > Import/Export. This starts the Import/Export wizard.
Select Import from another program or file, and then click Next.
Select Outlook Data File (.pst) and click Next.
Browse to the .pst file you want to import. Under Options, choose how you want to deal with emails and contacts, then choose Next.
If a password was assigned to the Outlook Data File (.pst), enter the password, and then click OK.
If you’re importing the contents of your .pst file into your Microsoft 365 mailbox, choose that mailbox here.
If you’re NOT importing into your Microsoft 365 mailbox, choose Import items into the current folder. This imports the data into the folder currently selected.
Choose Finish. Outlook starts importing the contents of your .pst file immediately. When the progress box disappears, the import is finished.