mark crossposts as expirable

[Roderick Schertler <roderick@argon.org>]

I'm getting started with using Gnus for mail.  I thought I might crosspost
messages into several groups (a group for each local user the message is
to or from, some other convenient designations which can be derived from
the header, that sort of thing) to make it easier to find messages later.

In order to make this work, though, I think I'll need a command to mark
the current article as expirable in all the groups its crossposted to
(for messages I would normally delete instead of saving).  Does anybody
have some code to do that?

-- 
Roderick Schertler
roderick@argon.org