To upload Thunderbird email to an Office 365 mailbox, we need a relevant solution that is MailsDaddy Thunderbird to Office 365 migration tool. The tool is developed on a simple GUI interface that helps any technical or non-technical user to import Thunderbird emails to Exchange Online. The tool has an auto-load button, through which a user can automatically load multiple mailbox data into the application and convert it to Office 365 account.