November 2, 2011
Earlier searches lead me to believe that storing sent mail on an IMAP folder was not feasible with Gnus.
So I was pleasantly surprised that setting:
; Store sent mail in a server IMAP folder on a per year basis (setq gnus-message-archive-group (format-time-string "nnimap+superbia:INBOX.Sent.%Y"))
Where “superbia” is the name of my IMAP server in my Gnus config.
Performance seems OK so far, so we’ll see how it turns out in the long run.