Carbonite - Unlimited online backup for one flat fee. Free trial, no credit card required.
Gmvault - Backup the emails in your Gmail account.
PieSync - Seamless two-way sync between your CRM, marketing apps and Google in no time
imapsync - Console-based utility for migrating IMAP mailboxes.
ShareGate Desktop - Cloud Migration
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.