Mail migration
Mail migration is a complicated topic that could support a small chapter by itself. There are four different types of migration into Exchange Online, as well as migration out of it.
A full discussion of migration is outside the scope of this book, because for the most part, by definition, it deals with areas outside of Office 365. We'll briefly touch on the types of migrations, and some of their prerequisites:
Migration to Exchange Online
Remote move migration
A remote move migration moves mail from an on-premises Exchange Server (2010 or higher) to Exchange Online. It can also be used in a hybrid deployment, to move mail between the on-premises Exchange and Exchange Online, in either direction. You'll need to enable the MRS Proxy on the on-premises Exchange Server.
Mailboxes moved in this way are specified in migration batches. You will use a CSV file to identify the specific mailboxes to be moved.
Staged migration
Staged migration is only available to organizations planning to...