I'd be interested in knowing if/how you can do this with other clients, e.g. Thunderbird... – JonikOct 20 '09 at 14:09
Almost all IMAP clients let you move mail back and forth from/to the IMAP server. So you would just drag the messages back to IMAP. (Although Thunderbird doesn't auto-move your mail to ~/mbox) – grawityOct 24 '09 at 9:45
~/mbox) – grawity Oct 24 '09 at 9:45