I have updated my 'Subject' to the localized string '[Chamado #{case}] {subject}' and cases are not being uniquely identified anylonger.
When the recipient hits Reply on any of the messages I send, with a subject line of, say, '[Chamado #44] Problema 1', a new case is created.
Question is: why don't you simply use that field content as a parameter to your email parser ?!? Sort of 'Chamado #' as THE key to identifying the case? Or even better, anything which is out of the { } pair?
Thanks for the excellent software, regards,