I'm looking for a mail archiving utility, or some suggestions for how to do it myself, and/or learning what others do.

I have quite a lot of incoming mail from lists like this, personal mail, etc. I read it and most of it gets deleted after a few days but some I save in a moderately deep directory hierarchy. E.g. I have

Mail/holidays/2005 Mail/holidays/2006 ... ... Mail/shopping/computers Mail/shopping/electrical ....

I'd like to move whole directories and/or mailboxes out of my 'current' mail hierarchy into a backup hierachy so that the backup hierarchy has everything in it whereas the current one is a bit more thinned out and up-to-date so it's easier to navigate.

I don't want to move mail out just on the basis of its date, last year's shopping is much less useful than last year's personal E-Mail for example.

I almost have what I want using rsync. I simply copy the whole of my current hierarchy to a backup (from here, which is remote, to my home system) with the --delete parameter. Then I make a further rsync copy from the backup to an archive area *without* the --delete. This means that if I delete a folder from my working E-Mail it also disappears from the backup but not from the archive.

The problem is that I want an easy to use tool to manipulate mail folders, if I'm sitting looking at my mail it's not all that easy to move stuff about from within my MUA. What would be perfect would be a way of marking messages/folders with a flag indicating that at the next overnight backup they should be moved to the archive.

Are there any mail archiving tools that can do my rsync trick but with an easier interface and/or can anyone suggest any other ways of getting what I want?

(BTW the mail is sitting on a remote BSD box to which I have ssh access, GUI tools for manipulating the mailboxes are probably not appropriate)