imapsync - Console-based utility for migrating IMAP mailboxes.
MailStore - MailStore Home - A 100% free single-private-user desktop solution
Intradyn Email Archiver - Orca Email Archiver provides email archiving solution for local government and business.
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.
Hornetsecurity Email Archiving - Hornetsecurity Email Archiving is one of the advanced software that offers long-term, unchangeable, and secure storage of important company information, data, and flies.
OfflineIMAP - OfflineImap synchronizes email between an IMAP server and a MailDir or between two IMAP servers.