In this regard, I recently read a helpful article that provides an in-depth manual method for importing Outlook OST into an Office 365 mailbox. Before you can import a PST file into Office 365, the OST files must first be converted into PST. In addition, it lets users quickly import OST files of a large size into the O365 platform. Before the conversion, users can quickly recover all damaged and inaccessible OST file databases here. This software's free demo version pack lets users convert thirty emails per mailbox without incurring any costs.
Features of PDS OST to Office365:-
Show preview of OST emails before importing OST to Office 365
OST to Office 365 Migration Tool allows user to Import OST to Office 365 in successful manner
Import OST Emails, Attachments, Calendar, Contact, Journals, Appointments and other items.
You can import single as well as multiple emails of OST files into Office 365 Account
Also maintains folder structure during OST to Office 365 migration.
Supported with Microsoft Outlook versions- 2019, 2016, 2013, 2010 and earlier versions.
Compatible with Windows OS up to 10 (32 and 64 Bit)
Easily import OST to Gmail and Office 365 with complete mailbox items