A method, server and system for optimizing and delivering HyperText Markup Language (HTML)-based content such as HTML-based email messages to mobile communication devices is provided. In accordance with one embodiment, the method comprises: receiving an email message comprising an HTML portion comprising an HTML header and an HTML body; determining if the HTML header includes a reference to a Cascading Style Sheet (CSS) document comprising one or more rules; if the HTML header includes a reference to a CSS document, replacing the reference with the CSS rules of the CSS document, and sending the transformed email message to a destination mobile communication device.