Did someone take a look at how other IMAP clients handles such
situation?

Weirdly enough, Gnus is the only one to show such issues, whereas I
can't recall ever having this problem in mutt nor seeing it in Evolution
or Thunderbird. And I don't believe in magic.

-- 
Julien Danjou
/* Free Software hacker * freelance consultant
   http://julien.danjou.info */