>>2
No, but you can easily write a GreaseMonkey script to locally alter any page to look however the fuck you want it.
>>5
If the client's email viewer doesn't support images, then she's shit out of luck. If the viewer does support images, then the solution in >>4 is ideal. The browser cannot detect whether or not the image is being served statically or dynamically (save for a few headers which can themselves be suppressed.)
I do agree that it's a retarded idea, but if someone wants to give me money for an easily implemented retarded idea I'm all for it. And this is such.
>>5
Actually it's the proper way to do it. Moreover, email clients cannot detect whether it is actually an image or a PHP script as this requires access to the server.