Microsoft 365 does not provide a simple built-in option to directly import an MBOX file into an Exchange Online mailbox. MBOX is commonly used by email applications such as Thunderbird and for email exports, while Microsoft 365 primarily works with Exchange mailbox data. As a result, moving MBOX emails to Microsoft 365 generally requires a compatible migration method.

The Aryson MBOX Migrator Tool can be used to transfer MBOX email data to Microsoft 365. It allows users to select MBOX files and connect the required Office 365 mailbox for migration. Depending on the MBOX data, the process can transfer email content, attachments, folder information, and metadata. Users should verify the migrated mailbox after the transfer to ensure the required data has been preserved.