Mass mailing refers to the practice of sending a large number of identical or similar messages, typically via email, to a wide audience. This method is often used for marketing or communication purposes, such as promoting a product or service, distributing newsletters, or sharing important updates with a large group of people. Unlike personalized emails, mass mailing does not target specific individuals and is often sent in bulk. While it can be an efficient way to reach a large audience, it can also be perceived as spam if not done carefully and ethically.