In case you are searching for secure and reliable ways to migrate the mailbox data from one Office 365 tenant to another Office 365 tenant then you should go through this informative article that explains the two approaches to perform the Office 365 Tenant to Tenant Migration. This article thoroughly provides a reference to the manual processes to accomplish this task. However, the manual method requires the proper knowledge of the Office 365 environment which makes it complex for non-technical users. 

In such a scenario, experts have always recommended opting for a professional Office 365 Migration Tool. This software is embedded with some smart functionalities that allow users to optimize the whole process. Additionally, it offers to backup and migrates the Office 365 mailbox data to various file formats and email clients. You can also try its free demo version in case you want to analyze the performance of this advanced utility.