Email spamming is a variant of email bombing; it refers to sending email to thousands of users (or to lists that expand to that many users). Email spamming can be made worse, if recipients reply to the email, causing all the original addressees to receive the reply.
It may also occur innocently, as a result of sending a message to mailing lists and not realizing that the list explodes to thousands of users, or as a result of an incorrectly set-up responder message.
Email bombing/spamming may be combined with email spoofing, which alters the identity of the account sending the email, thus making it more difficult to determine where the email is actually coming from.
Courtesy:- Legal Point Foundation