Saving emails

[Fulvio]

Hello,

my curiosity these day lay around the problem given by Kmail2.
I'd like to keep my old emails and a backup would satisfy my needs. The only 
conditions should be that the mails will come back in a quick way.
I found this page
http://www.ducea.com/2006/11/25/cleanup-maildir-folders-archive-delete-old-
mails/

Which gives me some point, but the program is too old and I'd like to use 
Python 3. Another chance it would be to implement an IMAP server which move 
old emails in and out of an archive. Then it will be simple to recall old 
emails.

Some docs about email deciphering. Kmail uses a maildir and several 
subfolders. I'd like to export the emails in mbox file and perhaps to 
separate by a period of time, say July2010, September2010 end so forth.

Thanks in advance