tedster - 5:36 pm on Apr 18, 2013 (gmt 0)
Email doesn't get opened in a browser per se
If my memory is correct, Outlook switched to using the rendering engine from MS Word instead of IE. That was an important security move from Microsoft.
However, today there are so many email clients that you have a huge spectrum to account for, not just a few "top" email clients. For example, just think about all the online email such as gmail, hotmail, etc. ANY browser might be used there, and they each have their own unique security steps for filtering any code included in the email. Then there are all the corporate and business email systems - it's immense.