Media richness theory, also referred to as information richness theory, is an important concept to understand as part of our quest to improve our information processing knowledge, media competencies, and Email processing capabilities.

Within communication theory, there are competing views as to if Email is a rich or a lean media. Email, according to traditional media richness theory, was believed to be a lean media because it is text-based, asynchronous in nature, and incapable of transmitting non-textual cues, such as facial expressions, body language, and tone.