I advise using the eSoftTools OST to PST Converter software if you have any doubts about how to import Outlook OST files into Office365. OST files can be converted by this software into PST and a variety of other file formats, including MBOX, EML, EMLX, Yahoo Mail, Gmail, Office365, Zimbra, vCard, ICS, CSV, and MSG. There is a 30-day money-back guarantee for this software. To ensure customer satisfaction, this product will offer a free demo version on the eSoftTools product website.

Know More:- https://www.esofttools.com/blog/how-to-import-ost-file-into-outlook-365-step-by-step-guide/

Importing an OST (Outlook Offline Data) file into Office 365 is not a straightforward process because OST files are typically associated with the cached mailbox on a specific computer and are not meant for import or export. However, if you want to access the data stored in an OST file in Office/Outlook 365, you'll need to convert it into a PST (Outlook Data) file first. For the conversion, you can use the GainTools OST to PST Converter which is the safest option to convert OST files in bulk and save them as PST or other file format. After that, you can import the PST file into your Office 365 account easily without getting into any trouble. Refer to know more: https://www.gaintools.com/ost/pst/

If you want to import Outlook OST files into Microsoft 365 then you can try Softaken OST to Office 365 Converter without using Outlook. This utility has various high-level features that make it popular among users. It's also a cost-effective tool that converts OST files into several file formats with a few clicks and retrieves data from corrupted or damaged Outlook OST files. As a result, it converts the bulk of Outlook OST data files with entire items such as Emails, Calendars, Contacts, and tasks, among other things. The tool also offers a full preview option after scanning your selected OST files. This utility supports all Windows and Outlook 2021, 2019, 2016, 2013, 2010, 2007, and 2003 versions.
Visit Here :- https://www.softaken.com/ost-to-pst-converter

You want to Import OST file into Outlook 365 step-by-step guide. I suggest the Mailvita OST to PST Converter Tool. This software converts OST files to PST file format and You can direct Import PST files to Outlook 365 account.. You can easily convert your OST files to PST file format. Import OST to PST Software is easy to use and 100% secure. Without any data loss, users can import bulk OST files to Outlook PST file format. The Offline OST file Property such as email, notes, events, contacts, calendars, drafts, tasks, journals, and attachments, is easy to convert to PST file format. This application supports all Mac and Windows OS versions.

Visit here: https://www.mailvita.com/ost-to-pst-converter-for-mac/

Using the Microsoft OST to PST Converter, you can easily import OST files into Outlook. It imports OST files to Office 365 with emails, contacts, calendars, notes, tasks, attachments, etc. The tool also converts OST files into PST, EML, MSG, MBOX, PDF, etc. Additionally, the tool imports OST files into Office 365, Thunderbird, Gmail, Hotmail, IMAP, AOL, etc. Download the free demo version of the tool.

Know more: https://www.msoutlookhelp.com/ost-to-pst-converter.html