mailbomb definition, from Internet Connection, Inc.

(also mail bomb) [Usenet]

1. v. To send, or urge others to send, massive amounts of email to a single system or person, esp. with intent to crash or spam the recipient's system. Sometimes done in retaliation for a perceived serious offense. Mailbombing is itself widely regarded as a serious offense — it can disrupt email traffic or other facilities for innocent users on the victim's system, and in extreme cases, even at upstream sites.

2. n. An automatic procedure with a similar effect.

3. n. The mail sent. Compare letterbomb, nastygram, BLOB (sense 2), list-bomb.