This post covers how to send html content in an email from CRM 2011.
Steps to follow:
1. Create a .html page with the html content that you need to include in your email and open it in a browser
2. Create a new email template in CRM 2011 and copy paste the html content from the browser to the message area in the Email Template
3. Save the Email Template
4. Create a new email and insert the Email Template which you just created with the required HTML content. When you write the C# code to create the email, just use the same Email template.