1. Sign in to the Google Admin console.
  2. Click Migrations.

    If you don't see Migrations on your dashboard, click More controls.

  3. Select the Email option and click Continue.
  4. On the Email Migration screen:
  5. Select Google Apps under Where are you migrating from? list,
  6. Select Auto select (recommended) under  connection protocol of the legacy mail server by doing one of the following actions:
  7. Enter the valid Google Admin credentials 
  8. Click Connect
  9. Select Start and end date to migrate  data 
  10. Chose whether to migrate deleted and junk email and whether to exclude specified folders from the migration. 
  11. Click Select Users.
  12. Hover over Add and click Select user.
  13. In the Migrate From field, enter the user's legacy email address.
  14. In the Migrate To field, start typing the user's new Google Apps email address and choose from the list of suggested users. 
  15. Click Start.