Everything is possible, if you a have an extensible email-reading application, written in one of the most powerful languages of the world:
;; Where to save a copy of all outgoing messages.
;; Save a copy in Gmail's special "Sent Mail" folder
;; and another one in "keramida", so that they appear
;; correctly in searches for "label:keramida" too.
(setq gnus-message-archive-group
(list "keramida" "[Gmail]/Sent Mail"))
What keramida said... 