This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Use the Apache Commons Email library, in particular the HtmlEmail class, to create an HTML email message. You can use any formatting you want inside the HTML content. Images can be added inline through the example on the class' Javadoc page.
I'd also use the setTextMsg method to set a plain text part for those clients that do not support HTML emails. This should be a simplified version of your HTML part without all the fancy formatting and images.