A bulk email is a single email sent to numerous recipients, which can be from hundreds, to thousands, to millions, and so on. Bulk emails can contain countless forms of content such as party invitations, newsletters, group messages, forwarded messages, announcements, mass emailing software reviews, marketing tools and tips, classified ads, and other kinds of emails. Most prominently, bulk emailing is used as a tool for email marketing campaigns which are now widely used by individuals or email marketing companies to promote their services or products.

Bulk email marketing refers to a form of marketing that involves sending the same, or nearly identical, message to multiple email recipients. This type of campaign requires special software that takes each individual email address from a pre-existing list, and distributes a single message to each one. The number of recipients can range from hundreds to thousands, depending on campaign objectives.