You can migrate Google Takeout emails into Office 365 by first extracting the MBOX files from the Google Takeout archive. Since Microsoft 365 does not directly support MBOX files, use the Aryson MBOX Converter Tool to add the extracted MBOX files, select the required emails, apply filters if needed, and choose Microsoft 365 as the destination. The tool then migrates the MBOX email data, including attachments, to the selected Microsoft 365 mailbox. This approach is useful for users who already have Gmail emails exported through Google Takeout and want to move them into Microsoft 365.

If you have downloaded your Gmail data using Google Takeout, the emails are generally available in MBOX format, which cannot be directly imported into Microsoft 365. For a large amount of data, manually converting and uploading the files can become complicated.

A simpler approach is to use SysTools MBOX to Office 365 Migration Tool, which can import MBOX files directly into Microsoft 365 mailboxes. You can add multiple MBOX files, map them to the required Microsoft 365 accounts, and migrate emails along with attachments and folder structure. It is especially useful for bulk migrations where handling each MBOX file manually would take considerable time.

Before starting a large migration, I would recommend testing a small mailbox first to verify the folder mapping and data structure.