imapsync - Console-based utility for migrating IMAP mailboxes.
Databarracks - Databarracks provides secure disaster recovery, online backup and Infrastructure as a Service.
Gmvault - Backup the emails in your Gmail account.
SysCloud - SysCloud offers backup solution helping businesses from data loss due to file corruption, accidental user error, and malicious acts.
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.
Veeam - Veeam develops backup, disaster recovery and virtualization management software for VMware and Hyper-V virtual environments.