Mule can be used to send emails with dynamically generated content using Velocity templates. Velocity templates allow using HTML tags to design colorful email bodies with images, logos, and dynamic text values pulled from property files. The example shows how to create a Velocity transformer class to set the email payload and map external values, use a properties file to define dynamic values, and write a Velocity template integrating the HTML tags, dynamic values, and file content into the email body. Testing confirms Mule successfully sends the email with the customized Velocity template design.