imapsync - Console-based utility for migrating IMAP mailboxes.
NeoCertified Secure Email - NeoCertified is a solution that provides secure email encryption for businesses and organizations across all industries, including healthcare, finance, legal, non-profit and education.
MailStore - MailStore Home - A 100% free single-private-user desktop solution
Virtru - Virtru is your data privacy force field, wrapping and protecting emails and files wherever they're shared. Easy-to-use data security software for business. People also askIs Virtru Hipaa compliant?
iSync - iSync is a software application published by Apple Inc.
Proofpoint Email Encryption - As email is the preferred medium for business communications, preventing confidential information from being leaked in outbound email messages must be a top priority in order to lower the risk of a data breach.