Eventually I hope to run my own mail server at home, but at the moment I use IMAP with my broadband ISP.

I use IMAP because it let's me keep track of what I have and haven't read between work, home and my girlfriends house and a central store for all the emails I've sent. The amount of space on the IMAP server I use is starting to get quite large because of a lot of attachments and I'm paranoid that my ISP is going to notice and delete some of my emails without informing me first. I've been backing up my inbox by downloading the emails via pop3 in Thunderbird to my desktop computer but leaving a copy on the server, but this only backs up my main inbox, not all my subfolders and sent and drafts folder.

How can I backup all my IMAP folders remotely?

Thanks

Ben