Microsoft Exchange to G Suite
Migrate your users' mail, contacts, and calendar data from a Microsoft® Exchange server using G Suite Migration for Microsoft Exchange (GSMME). If you use an IMAP server to route mail, you can also use GSMME to migrate the mail (including Gmail accounts) from the server to your G Suite accounts. See your options for routing mail from Google Accounts and IMAP servers.
For details, see What is GSMME?
For complete instructions on using GSMME, see the GSMME Administration Guide.