Bulk email is a nearly identical message which is sent to numerous recipients. Bulk email requires special bulk email software that takes each individual email address from that bulk email list, and sends one message to each email address.
Commonly, bulk email is used for newsletters or marketing email. If you have a list of customers or prospects, you can send them content relevant to their business or interest, from a single application. A bulk email service allows you to send to any list, regardless of its size.