To build this, apply the patch to the uw-imap-2004g source.

Then run:
make lnp SSLTYPE=none PASSWDTYPE=nul EXTRALDFLAGS=-static

and look for mailutil-hack executable in the mailutil/ folder.

This hacked version only works with "mailutil copy", expect to get an mbx format source and destination that is a unix format box. It keeps the message UIDs as well as the UIDVALIDITY and UIDLAST mailbox parameters during the copy.

Execution might look like:

mailutil-hack copy /full/path/to/mbx/folder '#driver.unix//full/path/to/new/folder'

You MUST use full paths to the folders unless you are running the file as the user whose mail folder you are migrating. If the path is not absolute, mailutil assumes it is relative to the current user's home directory.