||You may choose, scan, and upload PST files straight to Office 365 using a program for migrating Outlook PST to Office 365, such as Regain PST to Office 365 migration. The program begins by uploading the mail items from the chosen Outlook PST file to your Office 365 mailbox after establishing a secure connection to the mailbox using Microsoft Modern Authentication.
The program maintains the original folder hierarchy and structure. It generates mail folders and migrates the mail items if they are not already present in the mailbox. In order to prevent duplicate mail folders, it also combines the things in already-existing folders like Inbox, Sent Items, etc.
Read more: Import PST to Office 365