If you are using a signature, it can't be higher than 200 pixels, and can't be 500 pixels long (except in the case where your signature is just text only). If your signature wraps, it must fit under 200 pixels height nonetheless. The contents of your signature can't be larger 50 kilobytes neither. And it can't stretch the page no matter what. Also, your signature must not play music/sounds and must not slow down the browser in any way.

If you are using a signature, the maximum height for the immediate display of the signature is 200 pixels and the maximum width for the immediate display of the signature is 600 pixels. If your signature wraps, it must fit under the aforementioned maximum height under the resolution of 800x600. Your signature may not stretch the layout of the page at the resolution of 800x600 or larger unless contained inside a mechanism that hides the content until activated by the end-user to show the content. The contents of your signature may not be larger than 100 kilobytes, which includes both images and text except for fanclub images issued officially by the fanclub. Additionally, the signature may not cause load of plugins (such as Flash).