Plain and simple: Litmus makes testing email newsletters, websites and web-based solutions easy and quick. According to the owners, “It’s relied upon by thousands of smart freelancers and switched-on agencies; as well as big companies like Yahoo!, Facebook and eBay.” Plans range from free—which tests only IE 7 and Firefox 2 for websites and Outlook 2003 and Gmail for email newsletters—to unlimited individual and team accounts that allow you to run tests that examine your designs against 23 web browsers, 14 email clients, and 16 SPAM filters.

We like that they have a no questions asked money back guarantee and that there is no long term commitment required. Give it a test drive today!