There are many tools available on the Internet that can convert the PST file of your Outlook into a Office 365 mailbox, but I would like to suggest you a software which is very popular software on the Internet. You can securely move all your emails and other data of Outlook PST file in to Office 365 in just few clicks. This application also has Selective Conversion feature where you can easily Select those files which you want to Migrate. Visit:- https://www.softakensoftware.com/outlook-pst-to-office-365.html