You all probably know about subliminal advertising. For those who don't know about it, it is technique of inserting message, or picture, in commercials. Now, every second of video contains 24-29.97 frames depending of video format (PAL, NTSC). So, basically you can easily insert one frame between those bunch of frames with your message (those who saw "Fight club" movie will know about that ). So, when you are having commercial of e.g 1 minute, you can have 1440-1798.2 frames and about 60 frames of your desired message. Since eye usually cannot detect those frames you don't even see them, but since human brain works much faster than eye, those images are recorded "somewhere" in your brain, supposedly making you think about that message.

So what about email spam and same technique?
Like most of Internet users I receive great deal amount of spam. Today I have opened message, and since lots of them contains images I saw something unusual.Picture is GIF so since it supports animation, same technique is used. It reminds me on a movie "They live" since aliens are also using subliminal messages, with the difference that messages can only be seen with special glasses.  Now I don't know how efficient this is since, you can clearly see sub message, but makes you kinda think about, right ?

Since picture speaks as thousand words, here it is, so check it out. Just save it on Your hard drive, or take a look at it for a few seconds.