imapsync is a tool for facilitating incremental recursive IMAP transfers from one mailbox to another. It is useful for mailbox migration or backup, and reduces the amount of data transferred by only copying messages that are not present on both servers. Read, unread, and deleted flags are preserved, and the process can be stopped and resumed. The original messages can optionally be deleted after a successful transfer.
Information regarding Project Releases and Project Resources. Note that the information here is a quote from Freecode.com page, and the downloads themselves may not be hosted on OSDN.