To Migrate Exchange Archive Mailbox to Microsoft 365, large volumes of historical emails and attachments need to be organized and processed efficiently. Administrators can select the required mailbox data and apply filters before preparing it for migration. The Cigati Exchange Server to PST Backup Tool supports Exchange archive mailbox backup to PST format with mailbox selection, date-range filtering, and duplicate checking. This provides a structured way to prepare large archive datasets before moving them to the Microsoft 365 environment.