Yes, it is possible to transfer multiple Yahoo Mail accounts to Office 365 at the same time. This is particularly useful for businesses and organizations that need to migrate several user mailboxes during a platform transition. The SysInfo Yahoo Backup Tool allows users to add multiple Yahoo accounts and migrate their emails and attachments to Office 365 in a streamlined manner, reducing the time and effort required for manual migration. More: https://www.sysinfotools.com/yahoo-backup.php