I see that this is an old thread but I have a similar question:
I do use IMAP and Thunderbird (PC) and Mail (Mac). So using IMAP I am able to view all my mail on the mail server.
HOWEVER, since my mailbox space is limited on the mail server, I use Local Folders (PC) and On My Mac folders (Mac) to keep an archive of my mail folders. I would like to have a system so that I can access my mail archives from both the Mac and PC. That is, have a mail archive folder on Dropbox, for instance, that I can access and sync from either platform.
Anyone heard of a workaround for this?
(I'd be willing to use Thunderbird on my Mac if it would help.)