imapsync - Console-based utility for migrating IMAP mailboxes.
Cloud FastPath - Cloud-orchestrated data movement service for migrating, syncing, and backing up digital content.
MailStore - MailStore Home - A 100% free single-private-user desktop solution
WANdisco Fusion Platform - WANdisco Fusion is a data replication product for Hadoop.
audriga Email and Groupware migration - Easily migrate your email, contacts, calendar items and tasks to your new provider or server. No software installation is required.
ShareGate Desktop - Cloud Migration