Package imapsync

http://github.com/imapsync/imapsync

imapsync is a tool for facilitating incremental recursive IMAP
transfers from one mailbox to another. It is useful for mailbox migration,
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.

Version: 2.229