Gmvault - Backup the emails in your Gmail account.
imapsync - Console-based utility for migrating IMAP mailboxes.
SpinBackup - Spinbackup is the most comprehensive SaaS Data Backup & Security solutions provider for G Suite. Try our 15-Day Free Trial Today!
Datto Backupify - Protect your business with backup.
Cryoserver - Cryoserver is an all-in-one email archiving solution that empowers you to preserve your email in a tamper-evident archive, making you transform your data into a useful archive for everyday use.
Got Your Back - Got Your Back (GYB) is a command line tool that backs up and restores your Gmail account.