I wanted to use an IMAP sync but after much experimenting with existing tools concluded that the protocol wasn't flexible enough for a proper two-way synchronis

I wanted to use an IMAP sync but after much experimenting with existing tools concluded that the protocol wasn't flexible enough for a proper two-way synchronisation. I can't remember the exact reasoning now but several years on I am using dovecot's excellent dsync protocol over SSH to keep my laptop in sync with a private mail server, and have never looked back. Combined with pine, exim and the excellent mairix (surprised not to see that mentioned yet) I enjoy a decent search on a fast MailDir implementation, with full offline support.