Microsoft 365: Export from your Microsoft 365 mailbox to a .pst file

Add your Microsoft 365 email account to an Outlook app, such as Outlook for Microsoft 365, Outlook 2016, or 2013. Then, you can use Outlook to move email, contacts, and calendar items into your Microsoft 365 mailbox. 

1.  your "source" email account to Outlook. For example, you might add your Gmail account to Outlook 2016. Wait a bit for all of your email and contacts to show up.
2.  your Microsoft 365 email account to Outlook. After you do this, Outlook will automatically sync with Microsoft 365. You'll see the contents of your Microsoft 365 mailbox appear in Outlook.
3. Choose from the export instructions to export your email from the source account to a .pst file.

For example, if you have Outlook 2016, choose Outlook 2013 and Outlook 2016: Export Outlook items from a .pst file.

1. For example, if you have Outlook 2010, choose Outlook 2010: Export Outlook items to a .pst file.

After your email data is exported to a .pst file, it's portable! You can import it to other email accounts. If you want to do this using Outlook, see Import email, contacts, and calendar from an Outlook .pst file.