Here is a solution for you: use eSoftTools OST to Office 365 Converter Software to migrate OST to Office 365. The PST file can be easily imported into your Office 365. This tool can effortlessly restore CC, BCC, To, From, and attachments from email folders. The file size isn't an issue when it comes to getting good converting results, and It also works with all versions of Windows. Users can download the free demo versions.
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