MigrationWiz from Bittitan is one of the best tools on the market allowing for migration of user mailboxes. Whether it's a google account, exchange account or IMAP, it will help you out. Last few months I'm part of migration project that is using Bittitan at its core. One of the signature features of this tool is the ability to migrate mailboxes from Office 365 tenant to Office 365 tenant. This is not something that every application can do. Another feature (and something I want to address today) is the ability to ask users for their logins and password to migrate their data from one tenant to another tenant. While in general, you shouldn't do that and you should use migration accounts with proper permissions sometimes you have no other choice.