imapsync - Console-based utility for migrating IMAP mailboxes.

Gmvault - Backup the emails in your Gmail account.

SpinBackup - Spinbackup is the most comprehensive SaaS Data Backup & Security solutions provider for G Suite. Try our 15-Day Free Trial Today!

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.

CloudAlly - CloudAlly is a cloud-to-cloud back-up utility. Popular with growing businesses, this tool automates backups of Box, G Suite, Office 365, OneDrive for Business, SharePoint Online, Salesforce Cloud and other cloud-based file-directory services.

Mail Backup X - Your one stop mail backup and archiving tool for Mac.