Editting RTC Jazz E-mail Messages

Hi I have seen a couple of references that Jazz messages (e-mails) can't be edited, but those answers are dates (back to 2010 and 2009).  Has this capability changed in V3.x or V4?   In particular our client has said continually that if there was a reference to the "Filed Against" attribute that would help them to identify the context of work, especially for those that manage a portfolio or program of projects.