imapsync - Console-based utility for migrating IMAP mailboxes.
OfflineIMAP - OfflineImap synchronizes email between an IMAP server and a MailDir or between two IMAP servers.
MailStore - MailStore Home - A 100% free single-private-user desktop solution
MigrationWiz - MigrationWiz provides on-demand mailbox migration services through a fully automated cloud-based...
Fetchmail - The Fetchmail Project
IMAP Upload - IMAP Upload is a tool for uploading a local mbox file to IMAP4 server.