One-liner to retrieve an email's recipients?

Hi all,

Anybody have a quick comment on good ways to retrieve an email's
recipients (e.g. To:, cc:) with an nmh command?  Perfectly happy to hear
there's no amazing solution and the closest thing would probably be a
custom mh-format — just noticed some old code which locates the file
with mhpath and then parses out the headers, which seems potentially
excessive..

Conrad