Packf-unseen packs copies of messages from a folder into a single file in the UNIX mbox format. Unlike the standard MH utility packf(1), this will track which messages have been copied in previous invocations, and will avoid re-copying them.
Packf-unseen uses MH sequences to mark and track seen messages.
It is intended that packf-unseen, as applied to syncing MH mail to a Palm handheld, be an interim measure; this support should be included in the pilot-link suite of tools.
The manual page is available.
Download the tarball here: packf-unseen.tar.gz (6k).