I would like to suggest you this third party tool Regain PST to Office 365 Migration Software that can Migrate PST to Office 365 Account in just few clicks. This Software Maintains the original Outlook PST data file format and retains the read/unread status of the PST emails. You can also see the preview of all emails items before the migration. This Software also offer free demo version where user can save their 30 emails per folder at free of cost.