This free utility isn't easy to use, but can backup and restore data to/from gmail accounts, and preserves labels. It can restore MBOX files taken from Google Takeout.
https://github.com/GAM-team/got-your-back
You can also use Thunderbird or Outlook to set up two accounts, and manually backup all folders.
https://takeout.google.com/settings/takeout
Keywords: Google Mail, Gmail, Backup, Restore, Sync, Clone, Archive, Thunderbird |