If you're trying to suggest that users upgrade or change their browser, you're fighting a losing battle. People who are using older browsers either can't change because their employer's network environment won't let them, or they don't have the technical knowledge to understand how or why they should change. In either case, there's nothing to be gained by preaching to them.
If you need to warn users that your site doesn't function well with Internet Explorer, then the burden is on you to design your site so that it's usable by just about any browser out there. The latest versions of IE support most of the latest features of HTML 5 and CSS 3, and there are good solutions for adding support for many of the most popular features to IE going back to IE8.
If you'll explain why you want to send a message to IE users, the solution may be simpler than you think.