IMAP, Psion to server

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Having long POP'd my email I recently switched to IMAP on a 7book. It's handy having access to my email folders on the remote IMAP server and being able to move or copy messages between them as well as from them to the 7book. However, it seems to be impossible to move or copy messages from the 7book to the remote server. What I especially had in mind was moving them from the 7book's "sent" folder to my "sent" folder on the IMAP server. Is this really impossible or I am missing something? Thanks.
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