Comment by dheera

In 99% of cases there's no reason to blanket block any particular browser. If you have features that cannot be implemented (e.g. vector graphics, WebGL), I'd say that directly to the user, i.e. "Sorry, this website requires a WebGL-enabled browser such as X, Y, or Z." This should be based on JavaScript feature detection targeting the specific feature you're looking for, and not the web browser version number. If it's just text and CSS there's no reason why you can't at least display something. It may not look correct in IE <=8 but at least the user will see something intelligible in most cases.