Mixmaster is secure enough unless you are spamming, distributing pictures nobody should or plotting world government decline. The server admins will get you for the first two cases and the CIA for the third. I should have thought to add that when I said proxy too I meant "anonymous" proxy, as much as any can be, Mixmaster is a decent enough way to do this, as is TOR, botnets (illegal) or ... well you get the idea, and if you don't use Mixmaster or TOR if you need to be anonymous and don't send the kind of thing that will get server admins or CIA after you...