The php[architect] site has a new tutorial posted giving you a step by step guide to sending HTML email with the combination of Drupal 7, Webform and Mandrill (the mail service by Mailchimp).

By default, Drupal is configured to send out plain text emails. For many developers, plain text email is sufficient and preferable to HTML email. HTML email is still, in this day and age, not guaranteed to render the same across email clients, more likely to be labeled as spam, and requires a significant amount of testing to make sure it works. Still, a minimally styled HTML message can be easier for recipients to read and help reinforce your brand/design (if you don’t depend on images to do so). In this article, we’ll look at the modules to install and configure to enable HTML emails and, specifically, how to change the default Webform email template to send submissions as HTML.

The tutorial comes in four different sections, each with plenty of description and some code to make it happen:

• Set up your site to send email
• Allow outgoing email to use HTML
• Formatting Outgoing Email
• Send Webform Submission as HTML Emails