After you get Outlook for your desktop, do these steps:
Add your "source" email account to Outlook on your desktop. Wait a bit for all of your email and contacts to show up.
Add your Office 365 email account to Outlook on your desktop.
Next, choose from theexport instructionsto export your email from the source account to a .pst file.
Choose from the import instructions (below) in this article to import your email to Office 365.
Article ID: 4026180 - Last Review: 29 Kor 2017 - Revision: 1