Or you can use imapsync; make sure you get the latest version from github as the version that ships with most Linux distros is really old. As it is written in P

Or you can use imapsync; make sure you get the latest version from github as the version that ships with most Linux distros is really old. As it is written in Perl you can run it on Linux, Mac, and Windows. It handles one way sync in either direction and two-way sync. It copies all the flags and whether emails are marked read etc.