You do realize that updating Flash in IE will not update Flash that
Firefox uses, right? IE uses the ActiveX version of Flash while
Firefox uses the regular Flash version. You would need to update
Flash from Firefox to get the version that Firefox uses.
Your ISP only offers IMAP and not POP? That seems strange to me. If
they do have POP I would recommend switching to that because it offers
everything that you are looking for. IMAP is not what you want.