Gmvault - Backup the emails in your Gmail account.
SolarWinds Backup - Modern server backup software
imapsync - Console-based utility for migrating IMAP mailboxes.
Zerto - Virtual replication & recovery solution
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.
ShadowProtect SPX - ShadowProtect backup and disaster recovery software ensures on-prem business systems and data are fully protected and always available.