mail archival idea/feature request

[Andrew Hobson <ahobson@eng.mindspring.net>]

The recent thread about mail archival got me thinking.  Maybe I'm
completely off the boat in the deep end, but here's how I'd like it to 
work.

At expiry time, instead of deleting the message, I'd like to move it
into another, non-expiring group.  That way I could archive all of my
incoming mail, but it would remain in the usual group until
expiration.  I could then determine at expiry time if I wanted to save
the message, and if so, which archival group to put it in.

I took a quick peek and I didn't see an easy way to do this, although
I'm a gnus neophyte.  It would seem to me that a customizable hook run
at expiry time that defaults to nnmail-delete-file-function (or
whatever is appropriate for the backend) would enable me to do what I
wanted.

I suppose I could deliver the mail to two groups at split time: one
for archival and one for usual purposes, but that seems less that
optimal.

Is there a way in pgnus to do this kind of archival?

Drew